RTC: add rtc-rs5c313 driver

Add an RTC driver for Ricoh RS5C313 RTC chip.

[akpm@linux-foundation.org: Zillions of coding-style fixes]
[akpm@linux-foundation.org: build fixes]
Signed-off-by: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>