Handle Active device changed A2DP <-> Hearing Aid

When the active device is changed from A2DP to Hearing aid,
Both BluetoothA2dp.ACTION_ACTIVE_DEVICE_CHANGED and
BluetoothHearingAid.ACTION_ACTIVE_DEVICE_CHANGED are broadcasted.
One of them may nullify the other, which resulted in null active routes.

By handling devices of each type separately, we can resolve the issue.

Bug: 159757784
Test: Manaully tested with A2DP devices only
Change-Id: I6d5b61ec9b8ddf447b3d36b14c0325953193ab3b