Stopping Face Unlock immediately on detaching from window fixes 7338808

The refactoring broke my fix for 7222226.  We need to stop Face Unlock without
any messaging delay when the window is detached to avoid it starting with an
invalid window, or stopping right after it restarts.

Change-Id: Iea23989ec2ab3ad7d1a57e2d1fb85163a6396024

Author: Steven Ross

policy/src/com/android/internal/policy/impl/keyguard/KeyguardFaceUnlockView.java

@@ -75,7 +75,7 @@ public void reset() {
     public void onDetachedFromWindow() {
         if (DEBUG) Log.d(TAG, "onDetachedFromWindow()");
         if (mBiometricUnlock != null) {
-            mBiometricUnlock.stopAndShowBackup();
+            mBiometricUnlock.stop();
         }
     }