Code cleanup in Zen Mode Settings

Changes in response to code review from automerged commit ag/3171711

Test: make -j40 RunSettingsRoboTests
Bug: n/a
Change-Id: I5df3db4e8ff421ca9911c84ae3f621a0e3d08092

src/com/android/settings/notification/ZenModeRuleSettingsBase.java

@@ -47,6 +47,10 @@ import com.android.settings.SettingsActivity;
 import com.android.settings.search.BaseSearchIndexProvider;
 import com.android.settings.search.Indexable;
 import com.android.settings.widget.SwitchBar;
+import com.android.settingslib.core.AbstractPreferenceController;
+
+import java.util.Arrays;
+import java.util.List;
 
 import java.util.Arrays;
 import java.util.List;
@@ -145,6 +149,11 @@ public abstract class ZenModeRuleSettingsBase extends ZenModeSettingsBase
         mZenMode.setDependency(getZenModeDependency());
     }
 
+    @Override
+    protected List<AbstractPreferenceController> getPreferenceControllers(Context context) {
+        return null;
+    }
+
     @Override
     public void onResume() {
         super.onResume();