net/mlx4_en: Expose port number through sysfs

Initialize dev_port with port number (0 based) to be accessed through
sysfs from user space.
Signed-off-by: Amir Vadai <amirv@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

@@ -2342,6 +2342,7 @@ int mlx4_en_init_netdev(struct mlx4_en_dev *mdev, int port,
 
 	SET_NETDEV_DEV(dev, &mdev->dev->pdev->dev);
 	dev->dev_id =  port - 1;
+	dev->dev_port = port - 1;
 
 	/*
 	 * Initialize driver private data