Use FooterPreference in xml explicitly

Removed the FooterPreferenceMixin from the AutoBrightness page.

Fixes: 138916403
Test: manual test

Change-Id: I131d5cede156e2dae890342d5b456f347b025e27

src/com/android/settings/display/AutoBrightnessSettings.java

@@ -37,8 +37,6 @@ public class AutoBrightnessSettings extends DashboardFragment {
     @Override
     public void onCreate(Bundle icicle) {
         super.onCreate(icicle);
-        mFooterPreferenceMixin.createFooterPreference()
-                .setTitle(R.string.auto_brightness_description);
     }
 
     @Override