Merge "audio: Add methods for controlling hw volume" am: 0ae51672 am: e4775104

Original change: https://android-review.googlesource.com/c/platform/hardware/interfaces/+/2255291



Change-Id: I9d7aa112a0b9f30fb0c48ffde2a198e6631658a3
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>