Optimize power for incoming SMS

- In the current implementation, a wakelock is acquired when SMS is
  received in IdleState. The wakelock is released 3 seconds after
  returning back to IdleState. This happens even during bootup when
  there are no pending messages to be handled.

- Add a change to ensure that while booting up, the wakelock is
  not held if there are no pending messages to be handled.

Test: manual - Send and receive SMS

Bug: 34801294
Merged-in: I30d9ac2ee312bac0cd720047037d9048b540ec3f
Change-Id: I30d9ac2ee312bac0cd720047037d9048b540ec3f