net/mlx4_en: fix error return code in mlx4_en_get_qp()

Fix to return a negative error code from the error handling
case instead of 0.

Fixes: 837052d0 ('net/mlx4_en: Add netdev support for TCP/IP offloads of vxlan tunneling')
Signed-off-by: NWei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlx4/en_netdev.c

@@ -632,8 +632,9 @@ static int mlx4_en_get_qp(struct mlx4_en_priv *priv)
 	if (err)
 		goto steer_err;
 
-	if (mlx4_en_tunnel_steer_add(priv, priv->dev->dev_addr, *qpn,
-				     &priv->tunnel_reg_id))
+	err = mlx4_en_tunnel_steer_add(priv, priv->dev->dev_addr, *qpn,
+				       &priv->tunnel_reg_id);
+	if (err)
 		goto tunnel_err;
 
 	entry = kmalloc(sizeof(*entry), GFP_KERNEL);