Audio : Fix a few minor issues with stream switcher class am: 035beba203

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

Change-Id: I42680884d9a0675065028500096d7b7dcc00ffdf
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>