Audio : Fix a few minor issues with stream switcher class am: 035beba203 am: f901f6a465 am: e54466ff88 am: 2ce73f1649

Original change: https://android-review.googlesource.com/c/platform/hardware/interfaces/+/2680756

Change-Id: Iece914beb5c307ad50f117714595beeef18f75cd
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>