Fix various java warnings

Change-Id: I4c4381e1755831df2c4f41279800fd6af173e4ed

src/org/lineageos/setupwizard/SubBaseActivity.java

@@ -38,10 +38,6 @@ public abstract class SubBaseActivity extends BaseSetupWizardActivity {
 
     protected abstract void onStartSubactivity();
 
-    protected void onSubactivityCanceled(Intent data) {
-        // Do nothing.
-    }
-
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         if (LOGV) {