[Provider Model] Fix preference summary not update.

- When activity enter onPause, the status will not update, then
 sub id of TelephonyManager keep same value after activity go back.

 - Solution: Everytime update the UI, and always get new
 TelephonyManager with the latest sub id.

Bug: 181196545
Test: atest passed.
Test: Manual test passed.
Change-Id: I1d65bbc06af66b97b6c85f40bed394da03213d06

src/com/android/settings/network/SubscriptionsPreferenceController.java

@@ -257,9 +257,10 @@ public class SubscriptionsPreferenceController extends AbstractPreferenceControl
     }
 
     private CharSequence getMobilePreferenceSummary(int subId) {
+        TelephonyManager tm = mTelephonyManager.createForSubscriptionId(subId);
         String result = mSubsPrefCtrlInjector.getNetworkType(
                 mContext, mConfig, mTelephonyDisplayInfo, subId);
-        if (!mTelephonyManager.isDataEnabled()) {
+        if (!tm.isDataEnabled()) {
             return mContext.getString(R.string.mobile_data_off_summary);
         }
         if (!result.isEmpty() && mSubsPrefCtrlInjector.isActiveCellularNetwork(mContext)) {