Ignore onPreferenceChange for top level preference

Top level preferences are handled in onClick. Returning true would 
toggle the state of the switcher.

Test: Manually tested App & content access page
Bug: 30909943
Change-Id: I9487044aa67c20c9cb0e9bb9de8911f17e05d808

src/com/android/settings/users/AppRestrictionsFragment.java

@@ -560,8 +560,9 @@ public class AppRestrictionsFragment extends SettingsPreferenceFragment implemen
                     }
                 }
             }
+            return true;
         }
-        return true;
+        return false;
     }
 
     private void removeRestrictionsForApp(AppRestrictionsPreference preference) {