bluetooth: conn: Fix bt_gatt_connected call

bt_gatt_connected should be only called, when there is no
connection error. Change fixes problem with receiving notifications
before connection.

Signed-off-by: Marek Pieta <Marek.Pieta@nordicsemi.no>

subsys/bluetooth/host/conn.c

@@ -138,7 +138,9 @@ static void notify_connected(struct bt_conn *conn)
 		}
 	}
 
-	bt_gatt_connected(conn);
+	if (!conn->err) {
+		bt_gatt_connected(conn);
+	}
 }
 
 static void notify_disconnected(struct bt_conn *conn)