PatchPanel: fix deadlock when releasing a patch am: 34e55a460c

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/av/+/22813518

Change-Id: I0dae493c2cd994563c48aeb2e79efa0c631f8063
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>