dev: remove duplicate 'skb->dev = dev' in dev_forward_skb()

This was added by commit 59b9997 (Revert "net: maintain namespace
isolation between vlan and real device").
In fact, before the initial commit - the one that is reverted -, this
statement was not present.
'skb->dev = dev' is already done in eth_type_trans(), which is call just
after.

Spotted-by: Alain Ritoux <alain.ritoux@6wind.com>
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/dev.c

@@ -1629,7 +1629,6 @@ int dev_forward_skb(struct net_device *dev, struct sk_buff *skb)
 		return NET_RX_DROP;
 	}
 	skb->skb_iif = 0;
-	skb->dev = dev;
 	skb_dst_drop(skb);
 	skb->tstamp.tv64 = 0;
 	skb->pkt_type = PACKET_HOST;