Merge "Only returns supported mixer attributes for USB output devices." into...

Merge "Only returns supported mixer attributes for USB output devices." into udc-dev am: 1df77b62 am: db1df361 am: 7dd2c7b9 am: 02a205b8

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/av/+/23175445



Change-Id: I8a663c59562599aed134c45eff595e4b37e7c3e0
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>