MountService: unlink death notification when unregistering listeners

Change-Id: I09045cfe67f7da84bc68a50fc5440ea2c6b754e5

Author: Ethan1983

services/java/com/android/server/MountService.java

@@ -1218,6 +1218,7 @@ public void unregisterListener(IMountServiceListener listener) {
             for(MountServiceBinderListener bl : mListeners) {
                 if (bl.mListener == listener) {
                     mListeners.remove(mListeners.indexOf(bl));
+                    listener.asBinder().unlinkToDeath(bl, 0);
                     return;
                 }
             }