- Add locking.
- Account for if the MC146818_NO_CENT_ADJUST flag is set we don't need
to check wheter year < POSIX_BASE_YEAR.
- Add some comments about mapping the day of week from the range the
generic clock code uses to the range the chip uses and which I meant
to add in the initial version.
- Minor clean-up, use __func__ instead of hardcoded function names in
error strings.
o in the rtc(4) front-end additionally:
- Don't leak resources in case mc146818_attach() fails.
- Account for ebus(4) defaulting to SYS_RES_MEMORY for the memory
resources since ebus.c rev. 1.22.