net/mlx5e: Call vxlan_get_rx_port() with rtnl lock

Hold the rtnl lock when calling vxlan_get_rx_port().

Fixes: b7aade15485a ("vxlan: break dependency with netdev drivers")
Signed-off-by: Matthew Finlay <matt@mellanox.com>
Reported-by: Alexander Duyck <alexander.duyck@gmail.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlx5/core/en_main.c

@@ -2938,8 +2938,11 @@ static void *mlx5e_create_netdev(struct mlx5_core_dev *mdev)
 		goto err_tc_cleanup;
 	}
 
-	if (mlx5e_vxlan_allowed(mdev))
+	if (mlx5e_vxlan_allowed(mdev)) {
+		rtnl_lock();
 		vxlan_get_rx_port(netdev);
+		rtnl_unlock();
+	}
 
 	mlx5e_enable_async_events(priv);
 	schedule_work(&priv->set_rx_mode_work);