LeAudio: Check for start request mutext before getting value am: 4fa63586

Original change: https://android-review.googlesource.com/c/platform/packages/modules/Bluetooth/+/3006539



Change-Id: I0e9770b056eef8269c6129e407a9486fd842f688
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>