xen-netfront: Remove the meaningless code

The function netif_set_real_num_tx_queues() will return -EINVAL if
the second parameter < 1, so call this function with the second
parameter set to 0 is meaningless.

Signed-off-by: Liang Li <[e-mail]>
Reviewed-by: David Vrabel <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/net/xen-netfront.c

···
 	np                   = netdev_priv(netdev);
 	np->xbdev            = dev;
 
-	/* No need to use rtnl_lock() before the call below as it
-	 * happens before register_netdev().
-	 */
-	netif_set_real_num_tx_queues(netdev, 0);
 	np->queues = NULL;
 
 	err = -ENOMEM;
···
 	xennet_disconnect_backend(info);
 	kfree(info->queues);
 	info->queues = NULL;
-	rtnl_lock();
-	netif_set_real_num_tx_queues(info->netdev, 0);
-	rtnl_unlock();
  out:
 	return err;
 }