mapping. This uses the new common code shared with amd64.
The RTC should only be accessed via EFI. There is no locking around it as
the spec only has this as a requirement for the PC-AT CMOS device.
Reviewed by: kib, imp
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D12595
with no creative content. Include "lost" changes from git:
o Use /dev/efi instead of /dev/efidev
o Remove redundant NULL checks.
Submitted by: kib@, dim@, zbb@, emaste@
