CFR: extend use of nitems() macro in the kernel.

Hello;

Using coccinelle, and some hand re-formatting, I generated a patch to
make use of the nitems() macro in sys, which is too big for
phabricator [1].

I was careful to exclude anything from the contrib directory or
any code that is shared with userland (as to not have to include
additional headers).

The patch is big but pretty safe, I think. The changes are small but
still it touches many files[1].

I would like some feedback on the convenience of doing such replacement.
If it is a good idea we could do the same for roundup2() and, in fact,
I think DragonFly has already done this.

Regards,

Pedro.

[1] https://people.freebsd.org/~pfg/patches/sys-nitems.diff

[2] For those too lazy to check [1], here is a list of affected files.

M       sys/amd64/amd64/amd64_mem.c
M       sys/amd64/amd64/machdep.c
M       sys/amd64/linux/linux_sysvec.c
M       sys/amd64/linux32/linux32_sysvec.c
M       sys/arm/amlogic/aml8726/aml8726_clkmsr.c
M       sys/arm/arm/db_interface.c
M       sys/arm/at91/at91_pmc.c
M       sys/arm/mv/armadaxp/armadaxp.c
M       sys/arm/ti/cpsw/if_cpsw.c
M       sys/arm/xscale/ixp425/ixp425.c
M       sys/boot/common/part.c
M       sys/boot/efi/loader/bootinfo.c
M       sys/boot/mips/beri/boot2/boot2.c
M       sys/boot/uboot/common/metadata.c
M       sys/cam/ata/ata_da.c
M       sys/cam/ata/ata_xpt.c
M       sys/cam/cam.c
M       sys/cam/scsi/scsi_all.c
M       sys/cam/scsi/scsi_cd.c
M       sys/cam/scsi/scsi_da.c
M       sys/cam/scsi/scsi_sa.c
M       sys/cam/scsi/scsi_xpt.c
M       sys/cam/scsi/smp_all.c
M       sys/compat/linux/linux_socket.c
M       sys/ddb/db_variables.c
M       sys/dev/adb/adb_kbd.c
M       sys/dev/advansys/adv_isa.c
M       sys/dev/advansys/advlib.c
M       sys/dev/advansys/adw_pci.c
M       sys/dev/advansys/adwlib.c
M       sys/dev/ae/if_ae.c
M       sys/dev/age/if_age.c
M       sys/dev/agp/agp.c
M       sys/dev/agp/agp_ali.c
M       sys/dev/agp/agp_amd64.c
M       sys/dev/aha/aha_isa.c
M       sys/dev/aic/aic.c
M       sys/dev/aic/aic_cbus.c
M       sys/dev/aic/aic_isa.c
M       sys/dev/ale/if_ale.c
M       sys/dev/altera/atse/if_atse.c
M       sys/dev/atkbdc/atkbd.c
M       sys/dev/atkbdc/atkbdc.c
M       sys/dev/atkbdc/psm.c
M       sys/dev/bktr/bktr_core.c
M       sys/dev/bwi/bwirf.c
M       sys/dev/bwn/if_bwn.c
M       sys/dev/cardbus/cardbus_cis.c
M       sys/dev/digi/digi.c
M       sys/dev/digi/digi_isa.c
M       sys/dev/dwc/if_dwc.c
M       sys/dev/ed/if_ed_hpp.c
M       sys/dev/ed/if_ed_isa.c
M       sys/dev/ed/if_ed_pci.c
M       sys/dev/fb/creator.c
M       sys/dev/fb/fb.c
M       sys/dev/fb/machfb.c
M       sys/dev/fb/vesa.c
M       sys/dev/fb/vga.c
M       sys/dev/flash/mx25l.c
M       sys/dev/hatm/if_hatm.c
M       sys/dev/hifn/hifn7751.c
M       sys/dev/hwpmc/hwpmc_amd.c
M       sys/dev/hwpmc/hwpmc_core.c
M       sys/dev/hwpmc/hwpmc_e500.c
M       sys/dev/hwpmc/hwpmc_mips24k.c
M       sys/dev/hwpmc/hwpmc_mips74k.c
M       sys/dev/hwpmc/hwpmc_mpc7xxx.c
M       sys/dev/hwpmc/hwpmc_octeon.c
M       sys/dev/hwpmc/hwpmc_uncore.c
M       sys/dev/hwpmc/hwpmc_xscale.c
M       sys/dev/if_ndis/if_ndis.c
M       sys/dev/jme/if_jme.c
M       sys/dev/kbd/kbd.c
M       sys/dev/le/if_le_isa.c
M       sys/dev/le/if_le_lebuffer.c
M       sys/dev/le/if_le_ledma.c
M       sys/dev/mlx/mlx.c
M       sys/dev/mxge/if_mxge.c
M       sys/dev/nand/nand_id.c
M       sys/dev/ncr/ncr.c
M       sys/dev/nctgpio/nctgpio.c
M       sys/dev/nfe/if_nfe.c
M       sys/dev/patm/if_patm_attach.c
M       sys/dev/pccard/pccard_cis_quirks.c
M       sys/dev/rc/rc.c
M       sys/dev/re/if_re.c
M       sys/dev/rl/if_rl.c
M       sys/dev/rndtest/rndtest.c
M       sys/dev/sf/if_sf.c
M       sys/dev/sge/if_sge.c
M       sys/dev/siba/siba.c
M       sys/dev/sio/sio.c
M       sys/dev/sound/isa/gusc.c
M       sys/dev/sound/pci/emu10kx.c
M       sys/dev/speaker/spkr.c
M       sys/dev/stge/if_stge.c
M       sys/dev/uart/uart_kbd_sun.c
M       sys/dev/uart/uart_subr.c
M       sys/dev/usb/input/ukbd.c
M       sys/dev/usb/serial/u3g.c
M       sys/dev/usb/serial/uchcom.c
M       sys/dev/usb/serial/umcs.c
M       sys/dev/usb/serial/uplcom.c
M       sys/dev/vkbd/vkbd.c
M       sys/dev/wbwd/wbwd.c
M       sys/fs/autofs/autofs.c
M       sys/fs/nfs/nfs_commonkrpc.c
M       sys/geom/part/g_part_bsd.c
M       sys/geom/part/g_part_ebr.c
M       sys/geom/part/g_part_ldm.c
M       sys/geom/part/g_part_mbr.c
M       sys/i386/i386/i686_mem.c
M       sys/i386/i386/machdep.c
M       sys/i386/ibcs2/ibcs2_sysvec.c
M       sys/i386/linux/linux_sysvec.c
M       sys/kern/kern_dump.c
M       sys/kern/kern_ffclock.c
M       sys/kern/kern_jail.c
M       sys/kern/kern_ktrace.c
M       sys/kern/subr_hash.c
M       sys/kern/subr_witness.c
M       sys/kern/sysv_msg.c
M       sys/kern/sysv_sem.c
M       sys/kern/uipc_usrreq.c
M       sys/mips/mips/db_interface.c
M       sys/mips/nlm/board.c
M       sys/mips/nlm/xlp_machdep.c
M       sys/mips/rmi/dev/nlge/if_nlge.c
M       sys/net/netisr.c
M       sys/net/rtsock.c
M       sys/netgraph/atm/ng_atm.c
M       sys/netgraph/bluetooth/socket/ng_btsocket.c
M       sys/netgraph/ng_gif_demux.c
M       sys/netgraph/ng_iface.c
M       sys/netgraph/ng_socket.c
M       sys/netinet/in_proto.c
M       sys/netinet/tcp_syncache.c
M       sys/netinet6/in6_proto.c
M       sys/netipsec/key.c
M       sys/netipsec/keysock.c
M       sys/netnatm/natm_proto.c
M       sys/netsmb/smb_smb.c
M       sys/nlm/nlm_prot_impl.c
M       sys/pc98/cbus/gdc.c
M       sys/pc98/cbus/pckbd.c
M       sys/pc98/cbus/scterm-sck.c
M       sys/powerpc/powerpc/db_trace.c
M       sys/powerpc/pseries/xics.c
M       sys/security/audit/audit_bsm_klib.c
M       sys/security/audit/bsm_errno.c
M       sys/security/audit/bsm_fcntl.c
M       sys/security/audit/bsm_socket_type.c
M       sys/sparc64/sparc64/db_trace.c
M       sys/sparc64/sparc64/elf_machdep.c
M       sys/sparc64/sparc64/trap.c
M       sys/vm/vm_pager.c
M       sys/x86/isa/atpic.c
M       sys/x86/x86/identcpu.c
M       sys/x86/x86/local_apic.c