Do not let device sleep after successful auth

Retrying auth, or succeeding is a strong signal that the user
is present. The device should not sleep, otherwise the keyguard
will be dismissed (as it should) but not automatically locked,
since screen timaeouts don't lock instantly.

Test: Manual
Fixes: 135967964
Change-Id: I9a8bcf0ddb80536719d093aab9e00c76d87ad24b