ag/22361082 and ag/22460413 have added a dialog preventing entering
FingerprintEnrollEnrolling. So showing toast and early return in
onCreate() will never be reached. This CL cleans up this obsolete code
block.
Bug: 283244022
Test: N/A
Change-Id: Ifc5f3d909a275c735035146e44f70d2b5d5b51e3