Fix wrong password attempt count in DevicePolicyManager

Keyguard wasn't resetting dpm's count when a successful password
was made.  The result is the device would get wiped earlier than
it should.

Also fixes a TODO left over from keyguard refactoring that
allowed face unlock to trigger the same logic (ouch!).

Fixes bug 7219258

Change-Id: I2bd13c50a9beb8225d3237e86d5e34b73d0eb3cf