Reset visibilities if mDummyControlTarget is the control target

The leash visibility won't be reset while the control target is changed
anymore. So we need to reset it when mDummyControlTarget gets the
control.

Fix: 156342134
Test: Open Camera and see if status bar is visible while receiving a
      heads up notification.
Change-Id: Ieca5b08f4342ec350bb57d333f1e34149050db45