vhost_net: add a missing error return

We accidentally left out this error return so it leads to some use after
free bugs later on.

Fixes: 0a0be13b8fe2 ("vhost_net: batch submitting XDP buffers to underlayer sockets")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/vhost/net.c

@@ -1244,6 +1244,7 @@ static int vhost_net_open(struct inode *inode, struct file *f)
 		kfree(vqs);
 		kvfree(n);
 		kfree(queue);
+		return -ENOMEM;
 	}
 	n->vqs[VHOST_NET_VQ_TX].xdp = xdp;