svn commit: r197501 - head/sys/dev/atkbdc

http://svn.freebsd.org/changeset/base/197501

would not be bad if someone is from developers who are develop the amd64 looked at the problem this commit

on arch amd64
this code

 p = BIOS_PADDRTOVADDR((regs.R_ES << 4) + regs.R_BX);
 if ((readb(p + 6) & 0x40) == 0)

page fault ot access violation when try to readb from p pointer

R_ES = 0xf000
R_BX = 0xe6f5

as result it is a bios rom area
on arch i386 this works but not work on amd64

would be better to use BIOS_PADDRTOVADDR
but we migrate to x86bios_offset to access rom bios area