dsa: fix skb->pkt_type when mac address of slave interface differs

When a dsa slave interface has a mac address that differs from that
of the master interface, eth_type_trans() won't explicitly set
skb->pkt_type back to PACKET_HOST -- we need to do this ourselves
before calling eth_type_trans().

Signed-off-by: Lennert Buytenhek <buytenh@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>