audio: Add DriverInterface::start method am: 49712b56d8 am: d8e545d9d8

Original change: https://android-review.googlesource.com/c/platform/hardware/interfaces/+/2647304

Change-Id: I597153ff5af74e3725d05967668bd761a7b35db7
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>