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

Fixes: 0a0be13b ("vhost_net: batch submitting XDP buffers to underlayer sockets")
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Acked-by: NMichael S. Tsirkin <mst@redhat.com>
Acked-by: NJason Wang <jasowang@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>