net/mlx4_core: destroy workqueue when driver fails to register

When driver registration fails, we need to clean up the resources allocated
before. mlx4_core missed destroying the workqueue allocated.

This patch destroys the workqueue when registration fails.
Signed-off-by: NWei Yang <weiyang@linux.vnet.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

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

@@ -2635,6 +2635,8 @@ static int __init mlx4_init(void)
 		return -ENOMEM;
 
 	ret = pci_register_driver(&mlx4_driver);
+	if (ret < 0)
+		destroy_workqueue(mlx4_wq);
 	return ret < 0 ? ret : 0;
 }