PhoneWindowManager: Release wakelock after headset detection.

- Device does not go to suspend mode after boots up with headset connected.
- Wakelock is not released properly if headsed is detected during boot up.
- Release wakelock in headset intent handler.

CRs-fixed: 384362

(cherry picked from commit 67ddd3c31c7a58aed89f12f956a4d29d58654ed7)

Change-Id: I09f81f4f0e4b2035b13acbb23f6c1dd7b84652c1