Schedule alarm state callbacks to occur even when device is idle

Bug: 26200446

Theoretically, the callback delivered by AlarmClock should ensure the
device is awake for delivery of the second intent that changes the
alarm state to FIRED.

This CL removes that reliance and schedules the AlarmManager callback
in a manner that will wake the device if it is dozing at the fire time.

Change-Id: Idaf41309850bd4d072b1c84c28b038ee0197c145