Remove Quicksettings footer in QuickQSPanel

Before this cl, the footer was normally invisible, except if the user
removed all tiles in quick settings, then it looks broken (see bug).
Now the area is blank.

Bug: b/35381410
Test: manually

Change-Id: I104a46cfe396c7d44704505cebe41066d26866c4

packages/SystemUI/src/com/android/systemui/qs/QuickQSPanel.java

@@ -49,6 +49,9 @@ public class QuickQSPanel extends QSPanel {
 
     public QuickQSPanel(Context context, AttributeSet attrs) {
         super(context, attrs);
+        if (mFooter != null) {
+            removeView((View) mFooter.getView());
+        }
         if (mTileLayout != null) {
             for (int i = 0; i < mRecords.size(); i++) {
                 mTileLayout.removeTile(mRecords.get(i));