veth: Dont kfree_skb() after dev_forward_skb()

In case of congestion, netif_rx() frees the skb, so we must assume
dev_forward_skb() also consume skb.

Bug introduced by commit 445409602c092
(veth: move loopback logic to common location)

We must change dev_forward_skb() to always consume skb, and veth to not
double free it.

Bug report : http://marc.info/?l=linux-netdev&m=127310770900442&w=3

Reported-by: Martín Ferrari <martin.ferrari@gmail.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
char *netdev_drivername(const struct net_device *dev, char *buffer, int len)
{
	const struct device_driver *driver;
	const struct device *parent;

	if (len <= 0 || !buffer)
		return buffer;
	buffer[0] = 0;

	parent = dev->dev.parent;

	if (!parent)
		return buffer;

	driver = parent->driver;
	if (driver && driver->name)
		strlcpy(buffer, driver->name, len);
	return buffer;
}

char *netdev_drivername(const struct net_device *dev, char *buffer, int len)
{
	const struct device_driver *driver;
	const struct device *parent;

	if (len <= 0 || !buffer)
		return buffer;
	buffer[0] = 0;

	parent = dev->dev.parent;

	if (!parent)
		return buffer;

	driver = parent->driver;
	if (driver && driver->name)
		strlcpy(buffer, driver->name, len);
	return buffer;
}
