audio: Add DriverInterface::start method am: 49712b56d8 am: d8e545d9d8 am: 4eb39af463

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

Change-Id: Ib7f0bf5f5c912c46d0544348a9f52307437245df
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>