rtc: convert DS1374 to dev_pm_ops

There is a general move to replace bus-specific PM ops with dev_pm_ops in
order to facilitate core improvements. Do this conversion for DS1374.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: john stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>