Define ICON_UNAVAILABLE for no icon status

Bug: 147776885
Test: make -j42 RunSettingsRoboTests
Change-Id: I0fd0e203bb7590955d0caf2679ebc78be68b4e50

src/com/android/settings/panel/PanelFragment.java

@@ -193,7 +193,7 @@ public class PanelFragment extends Fragment {
         loadAllSlices();
 
         final int iconRes = mPanel.getIcon();
-        if (iconRes == -1) {
+        if (iconRes == PanelContent.ICON_UNAVAILABLE) {
             mTitleView.setText(mPanel.getTitle());
         } else {
             mTitleView.setVisibility(View.GONE);