Add screen resource for Colors setting.

- each preference fragment should have its own preference screen layout
in order to show the title correctly. Adding the missing data for
ColorModePreferenceFragment.

Change-Id: I172429dc957f94351456d4bc829897a578d7dbf9
Fixes: 68763217
Test: make RunSettingsRoboTests

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

@@ -44,6 +44,11 @@ public class ColorModePreferenceFragment extends RadioButtonPickerFragment {
         mController = new NightDisplayController(context);
     }
 
+    @Override
+    protected int getPreferenceScreenResId() {
+        return R.xml.color_mode_settings;
+    }
+
     @Override
     protected List<? extends CandidateInfo> getCandidates() {
         Context c = getContext();