Reset view flipper alpha to 1.

I've seen insteances of the inset animation setting the view flipper
alpha to 0 where end is never called and the alpha never gets reset to
1. When we start the appear animation, we want to ensure that the view
flipper alpha is set to 1.

Fixes: 261730718
Test: Open and close bouncer in password and then change security method
to pattern and open and close bouncer.

Change-Id: I69deffb7f9828ecbe851b8feb8335a9b1fd87499