Do not close /dev/alarm before the final rtc wakeup programming

Both /dev/alarm and /dev/rtc should be reprogrammed on dsme exit.

If /dev/alarm is closed before that, the we might end up using
the previously programmed actual alarm time instead of the one
minute before we want.

[iphb] Do not close /dev/alarm before the final rtc wakeup programming
Merge pull request #36 from spiiroin/powerup_alarm

Do not close /dev/alarm before the final rtc wakeup programming