hal: Add support for multiple instances of offload playback

Add support for multiple offload playback instances

Change-Id: I9d35b68fc8ca27c4eeb3976eb508b06c5ad3ca8f
hal: configure HDMI channels based on sink capability.

- configure output HDMI channel count based on sink
  capability when audio.use.hdmi.sink.cap is set to true

CRs-Fixed: 656308
Change-Id: I3dd3226054c68a69a2c29f8bb2f9c27e429ad2dc