Fix the settings crash when SimDialogActivity is null

The PreferredSimDialogFragment did updateDialog after SimDialogActivity
was finished. It caused the settings crash. This is similar to b/184899699

Bug: 220803944
Test: build pass
Change-Id: I9a5964400a63053e362632944b9e7aa8ec1bbea8
(cherry picked from commit 70bf76a436)

src/com/android/settings/sim/PreferredSimDialogFragment.java

@@ -84,10 +84,11 @@ public class PreferredSimDialogFragment extends SimDialogFragment implements
     private void updateDialog(AlertDialog dialog) {
         Log.d(TAG, "Dialog updated, dismiss status: " + mWasDismissed);
 
-        final SubscriptionInfo info = getPreferredSubscription();
         if (mWasDismissed) {
             return;
         }
+
+        final SubscriptionInfo info = getPreferredSubscription();
         if (info == null) {
             dismiss();
             return;