FactoryResetPreferenceController return null when permission isn't

grandted.

Flag: EXEMPT bugfix
Bug: 396580123
Test: manual
Change-Id: Id68dcebc600de21fddf8801757dfb56b92a1a773

src/com/android/settings/system/FactoryResetPreferenceController.java

@@ -111,7 +111,7 @@ public class FactoryResetPreferenceController extends BasePreferenceController {
                     return prepareFactoryResetWizardRequest;
                 }
             }
-            return prepareFactoryResetWizardRequest;
+            return null;
         }
         Log.i(TAG, "Unable to resolve a Factory Reset Handler Activity");
         return null;