leaudio: Make sure Audio HAL is always notified corretly

With this patch if internal state of the sink/source changes, we make
sure audio hal is notified.

Bug: 216466543
Bug: 150670922
Test: atest --host bluetooth_le_audio_test
bluetooth_le_audio_client_test
Sponsor: @jpawlowski

Change-Id: Ib2dd573804adefbad5c0f445766ae22c26bdefa1