rtc-cmos: fix wakeup from S5 without CONFIG_PM_SLEEP

Commit b5ada460 ("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.

Signed-off-by: Daniel Glöckner <daniel-gl@gmx.net>
Cc: Mika Westerberg <mika.westerberg@linux.intel.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>