rtc: add RTC driver for TPS80031/TPS80032

Add an RTC driver for TPS80031/TPS80032 chips by TI.  This driver
supports:
 - Setting and getting time and date.
 - Setting and reading alarm time.
 - Alarm and interrupt functionlity.

[akpm@linux-foundation.org: remove obsolete __devinit/__devexit]
Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Reviewed-by: Devendra Naga <devendra.aaru@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>