audio: Fix the comment about threading of DriverInterface::init am: 3755134720

Original change: https://android-review.googlesource.com/c/platform/hardware/interfaces/+/2597780

Change-Id: I669e578fd127a6a775f0170b58ff6bc03958ce98
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>