Merge "AS: only dispatch preferred mixer attributes change if the device is...

Merge "AS: only dispatch preferred mixer attributes change if the device is found." into udc-dev am: ceabef76 am: ac14ce4b

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/22126832



Change-Id: Id3d67c7ccc037784e45d39b37cd53871e47cb239
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>