Revert "RTC: sa1100: remove redundant code of setting alarm"

This reverts commit 42874759.

This wasn't tested as a stand-alone patch, and it has build errors
without the following patches applied:

drivers/rtc/rtc-sa1100.c: In function 'sa1100_rtc_set_alarm':
drivers/rtc/rtc-sa1100.c:208: error: 'now' undeclared (first use in this function)
drivers/rtc/rtc-sa1100.c:208: error: (Each undeclared identifier is reported only once
drivers/rtc/rtc-sa1100.c:208: error: for each function it appears in.)
drivers/rtc/rtc-sa1100.c:210: error: incompatible type for argument 3 of 'rtc_next_alarm_time'
drivers/rtc/rtc-sa1100.c:211: error: 'time' undeclared (first use in this function)

So it too gets reverted to bring us back to a working point.