Fix 5458658: Fix memory leak in lock screen

This fixes a memory leak caused by not unregistering the info callback
held when LockPatternKeyguardView gets destroyed.

Change-Id: I8c008b6f8a5e8471bd0e1fd3939aa75175923ce5

policy/src/com/android/internal/policy/impl/LockPatternKeyguardView.java

@@ -767,6 +767,7 @@ public class LockPatternKeyguardView extends KeyguardViewBase implements Handler
             this.removeView(mUnlockScreen);
             mUnlockScreen = null;
         }
+        mUpdateMonitor.removeCallback(this);
     }
 
     private boolean isSecure() {