Update notes for submitted changes

* hal/usb: Add initial volume setting for USB headset
* hal: Fix VoIP Mute failure in SIP call during Voice call HOLD
* Audiod: Priority change for AudioDaemon
* audio: Remove unused var 'update_mixer'
* hal: Correct PCM offload fragment size
* Revert "  hal: Fix device disable/enable sequence"
* hal: Set echo reference from mixer file