drivers/rtc/rtc-jz4740.c: add alarm function

Add the "alarm" function to the jz4740 RTC.  Interrupts will now be raised
when the "alarm" time is reached.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Cc: Wan ZongShun <mcuos.com@gmail.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Lars-Peter Clausen <lars@metafoo.de>
Cc: Paul Gortmaker <p_gortmaker@yahoo.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>