Alarm: ignore less than 2 mins upcomming power off alarm

2 minutes is our define for enough boot up time for a power off alarm.
For current design, it can only afford upcoming power off alarm which
is later than 2 minutes. Kernel alarm driver only take care the power
off alarm which is 2 minutes later. And the framework only pass the
first power off alarm to kernel. So we need to find the first 2
minutes later upcomming power off alarm to kernel, otherwise it will
be no power off alarm from kernel's perspective. Fix the bug by
ignoring less than 2 mins upcomming alarm as power off alarm, and
only treat it as a normal alarm.

CRs-Fixed: 624561
Change-Id: I91379ecb2b378441ac2edb36212531ba6f203d8a