sms: Workaround a bug in the db layer and update the data

The sync with the database might fail. Reread the updated
subscriber after we have written it. The source of this
failure is unknown.
diff --git a/openbsc/src/sms_queue.c b/openbsc/src/sms_queue.c
index 89daf1f..c03b369 100644
--- a/openbsc/src/sms_queue.c
+++ b/openbsc/src/sms_queue.c
@@ -152,6 +152,9 @@
 		     "Subscriber %llu is not reachable. Setting LAC=0.\n", pending->subscr->id);
 		pending->subscr->lac = GSM_LAC_RESERVED_DETACHED;
 		db_sync_subscriber(pending->subscr);
+
+		/* Workaround a failing sync */
+		db_subscriber_update(pending->subscr);
 	}
 
 	sms_pending_free(pending);