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

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

Change-Id: I4246509623a4c4fe3a4f9847673e3a3a98fc44ce
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>