r247835: drm2 code breaks buildkernel

On r247835 build kernel fails:

cc -O2 -pipe -O3 -pipe -march=native -O3 -march=native -pipe
-fno-strict-aliasing -Werror -D_KERNEL -DKLD_MODULE -nostdinc
-DHAVE_KERNEL_OPTION_HEADERS -include
/usr/obj/usr/src/sys/GATE/opt_global.h -I. -I_at_ -I_at_/contrib/altq
-fno-common  -fno-omit-frame-pointer -I/usr/obj/usr/src/sys/GATE
-mno-aes -mno-avx -mcmodel=kernel -mno-red-zone -mno-mmx -mno-sse
-msoft-float  -fno-asynchronous-unwind-tables -ffreestanding
-fstack-protector -std=iso9899:1999 -Qunused-arguments -fstack-protector
-Wall -Wredundant-decls -Wnested-externs -Wstrict-prototypes
-Wmissing-prototypes -Wpointer-arith -Winline -Wcast-qual  -Wundef
-Wno-pointer-sign -fformat-extensions  -Wmissing-include-dirs
-fdiagnostics-show-option  -Wno-error-tautological-compare
-Wno-error-empty-body  -Wno-error-parentheses-equality -c
/usr/src/sys/modules/drm2/drm2/../../../dev/drm2/drm_ioctl.c
/usr/src/sys/modules/drm2/drm2/../../../dev/drm2/drm_global.c:63:27:
error: unused variable 'item' [-Werror,-Wunused-variable]
                struct drm_global_item *item = &glob[i];
                                        ^
1 error generated.
*** [drm_global.o] Error code 1


Just for the record,

oh