Due to changes to enforce checking interface bindings,
sockets did not see loopback packets bound for our local address
on our interface.

e.g.)
  When we ping6 fe80::1%eth0, skb->dev points loopback_dev while
  IP6CB(skb)->iif indicates eth0.

This patch fixes the issue by using appropriate incoming interface,
in the sense of scoping architecture.
Signed-off-by: NYOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>