Removed makeInvisible() function

This is now being done inside stopUI instead of its own separate
call since it needs to be done on the UI thread inside FaceLockService.

Change-Id: Iaf3a203f7f201ba4dde4c878f457e765f11e6c0e

core/java/com/android/internal/policy/IFaceLockInterface.aidl

@@ -23,7 +23,6 @@ interface IFaceLockInterface {
     void startUi(IBinder containingWindowToken, int x, int y, int width, int height,
             boolean useLiveliness);
     void stopUi();
-    void makeInvisible();
     void registerCallback(IFaceLockCallback cb);
     void unregisterCallback(IFaceLockCallback cb);
 }