Sound Control: WCD9320: expose additional controls

Change-Id: I7a087536dd35f823fbb63d1adfddd1c423805543
sound control 3.x: Initial GPL release for WCD9320 Audio Codec

Change-Id: I871e518dd75cb315cc9804876b9333cd7390b994
sound control: WCD9320: update speaker gain control for Z1

Signed-off-by: Paul Reioux <reioux@gmail.com>
Sound Control: (OPTIONAL) add power amp registers access control as well

Change-Id: I0f57ee9ad53842f7bfa51c2ef01b3f74b46ea930
 sound control: add register cache

Change-Id: I187482ade0c10af893a461465b5b3492b4607a17