Do not setListener(null) onViewDetached

There's currently a race condition upon orientation changes that
causes the new view to be attached before the old view is detached.
This results in a null listener.

Fixes: 193056436
Test: Start enroll, rotate, continue enroll
Change-Id: Id6c93dc9ee847aed0fb4a7eefbb7690a5c972781

packages/SystemUI/src/com/android/systemui/biometrics/UdfpsEnrollViewController.java

@@ -71,12 +71,6 @@ public class UdfpsEnrollViewController extends UdfpsAnimationViewController<Udfp
         }
     }
 
-    @Override
-    protected void onViewDetached() {
-        super.onViewDetached();
-        mEnrollHelper.setListener(null);
-    }
-
     @NonNull
     @Override
     public PointF getTouchTranslation() {