Let lock icon reappear after fingerprint draw off

Test: Unlock with fingerprint, observe icon
Test: Unlock with fingerprint while collapsing panel, make sure
icon reappears after 800ms.

Change-Id: I8b081445bdaaa68741e4bab57a6f79f6e12f1d54
Fixes: 30507748
(cherry picked from commit 8dea48c8)