Fix AudioService on HFP power off due to new Bluetooth API.
Fix AudioService on HFP power off due to new Bluetooth API.

HEADSET_STATE_CHANGED_ACTION contains a null BluetoothDevice when the HFP
disconnects.

xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base