1. Start alarm thread when device enters power off charging mode.
Reboot the device when alarm time is up during power off charging.
2. Add reboot function to event data.If the alarm event happens, call
reboot function immediately to ensure that device won't go to suspend
during calling reboot function.
3. Add alarm seconds check in case of that power off alarm time is up
when start alarm thread. If the final alarm time is less than the
estimated time of next boot completed to fire, that means it is not able
to fire the last power off alarm at the right time, so just miss it.
CRs-Fixed: 2054302
Change-Id: I40bd9c35a9e42aeabb742603e161c2049cd0b5f5
Mao Jinlong