Quick unlock : Fix bug

There is an issue where users whose passwords are greater than 8 chars and
have quick unlock enabled will be unable to unlock their lockscreen.
This is due to the logic evaluating anything beyond 3chars as a password attempt.

This change modifies the quick unlock behavior so that when typing the password,
each character is considered an attempt, however if incorrect, is not reported as a failed attempt.
Only when the user presses enter is it considered an "explicit" attempt and a failed attempt is reported.

Change-Id: I02d436184d63c6880c7b1dc6b4b6119fba76e9a7