Fixed UserVisibilityMediator so it doesn't suppoort invalid modes.

Test: atest UserVisibilityMediatorSUSDTest UserVisibilityMediatorMUMDTest UserVisibilityMediatorMUPANDTest
Fixes: 271326329

Change-Id: Ia9da8bd87a4178c9b42b56f3afb82eb82f3120c8
3 files changed