Commit b5ada4600dfd ("drivers/rtc/rtc-cmos.c: fix compilation warning
when !CONFIG_PM_SLEEP") broke wakeup from S5 by making cmos_poweroff a
nop unless CONFIG_PM_SLEEP was defined.
Fix this by restricting the #ifdef to cmos_resume and restoring the old
dependency on CONFIG_PM for cmos_suspend and cmos_poweroff.