A2DP: Prevent NPE in getDevicesMatchingConnectionStates()

* Add a check for states == null
* Use AdapterService.getBondedDevices() instead of
  BluetoothAdapter.getBondedDevices()

Bug: 74342889
Test: Instrumentation test
Change-Id: I86192161d631d4f47a10794f12f8477577a75554
1 file changed