[PATCH] AT91rm9200 RTC can issue system wakeup events

This lets the at91rm9200 RTC alarm be a system wakeup irq, according to the
setting of /sys/devices/platform/at91_rtc/power/wakeup.  User code can set the
alarm, put the system into a low power mode, and then rely on it waking up no
later than the specified moment.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>