Fixed problem where Face Unlock area was showing

I introduced a bug cl https://android-git.corp.google.com/g/#/c/141926
that caused black box to hide lock pattern even when not using Face
Unlock.

Fixed by adding the corresponding check to make sure Face Unlock is
being used.

Change-Id: I9c429c99d7db4d1ab831080f23a1e10123dbfe3e