mlx4_en: fix allocation of device tx_cq

The memory to hold the network device tx_cq is not being allocated with
the correct size in mlx4_en_init_netdev(). It should use MAX_TX_RINGS
instead of MAX_RX_RINGS. This can cause problems if the number of tx
rings being used is greater than MAX_RX_RINGS.
Signed-off-by: Kleber Sacilotto de Souza <klebers@linux.vnet.ibm.com>
Acked-by: Amir Vadai <amirv@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

@@ -2067,7 +2067,7 @@ int mlx4_en_init_netdev(struct mlx4_en_dev *mdev, int port,
 		err = -ENOMEM;
 		goto out;
 	}
-	priv->tx_cq = kzalloc(sizeof(struct mlx4_en_cq) * MAX_RX_RINGS,
+	priv->tx_cq = kzalloc(sizeof(struct mlx4_en_cq) * MAX_TX_RINGS,
 			      GFP_KERNEL);
 	if (!priv->tx_cq) {
 		err = -ENOMEM;