drivers/rtc/rtc-tps65910.c: remove unnecessary irq stat save and restore

The driver stores the interrupt enable register before going to suspend
and restore in resume.  Also it enables alarm before going to suspend.

The driver only write the Interrupt enable register for enabling ALARM and
does not enable any other bits.  So it is not require to save complete
register and enable ALARM interrupt before suspend and restore in resume.

Also ALARM interrupt already enable if alarm is enabled before going to
suspend and hence it is not require to enable explictly in suspend.

Removing such above code.

Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Cc: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>