[ARM] pxa/sa1100: replace wakeup support

Replace wakeup support using the alarm via the SA1100 RTC driver on
SA1100 and PXA platforms.  This allows RTC alarm wakeup to be enabled
via sysfs using the conventional attributes.

Acked-by: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>