Centering FUL fixes b/7480608

A simple one-line change to center FUL horizontally.  This looked
really bad on tablets when the charging text was showing as FUL was
obviously off-center compared to the text.  It was also off-center
on phones, which looked particularly bad when going to the backup.

Change-Id: Id0e3039a67c9bb746a8c9948e82ff87b6c815e1b

Author: Brian Colonna

core/res/res/layout/keyguard_face_unlock_view.xml

@@ -44,6 +44,7 @@
            android:id="@+id/face_unlock_area_view"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
+           android:layout_gravity="center_horizontal"
            android:background="@*android:drawable/intro_bg"
            android:gravity="center">