rtc-cmos: fix suspend/resume

rtc-cmos was setting suspend/resume hooks at the device_driver level.
However, the platform bus code (drivers/base/platform.c) only looks for
resume hooks at the dev_pm_ops level, or within the platform_driver.

Switch rtc_cmos to use dev_pm_ops so that suspend/resume code is executed
again.

Paul said:

: The user visible symptom in our (XO laptop) case was that rtcwake would
: fail to wake the laptop.  The RTC alarm would expire, but the wakeup
: wasn't unmasked.
:
: As for severity, the impact may have been reduced because if I recall
: correctly, the bug only affected platforms with CONFIG_PNP disabled.

Signed-off-by: Paul Fox <pgf@laptop.org>
Signed-off-by: Daniel Drake <dsd@laptop.org>
Acked-by: Rafael J. Wysocki <rjw@sisk.pl>
Cc: <stable@kernel.org>		[2.6.37.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>