veth: allow to setup multicast address for veth device

We can only setup multicast address for network device when
net_device_ops->ndo_set_rx_mode is not null.

Some configurations need to add multicast address for net
device, such as netfilter cluster match module.

Add a fake ndo_set_rx_mode function to allow this operation.
Signed-off-by: Gao feng <gaofeng@cn.fujitsu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/veth.c

@@ -188,6 +188,11 @@ static struct rtnl_link_stats64 *veth_get_stats64(struct net_device *dev,
 	return tot;
 }
 
+/* fake multicast ability */
+static void veth_set_multicast_list(struct net_device *dev)
+{
+}
+
 static int veth_open(struct net_device *dev)
 {
 	struct veth_priv *priv = netdev_priv(dev);
@@ -250,6 +255,7 @@ static const struct net_device_ops veth_netdev_ops = {
 	.ndo_start_xmit      = veth_xmit,
 	.ndo_change_mtu      = veth_change_mtu,
 	.ndo_get_stats64     = veth_get_stats64,
+	.ndo_set_rx_mode     = veth_set_multicast_list,
 	.ndo_set_mac_address = eth_mac_addr,
 };