audio: Add support for FLAC in compress offload path

- Add new audio format for FLAC
- Add FLAC in valid formats list
- Add bitWidth in offload info

Change-Id: Ic716aff8b7cdb28b03f32f686eca33ff0beb981c
(cherry picked from commit 967310abb86170ee2afa2a81886e53e5d63e40a5)