nf_hook() can free the skb, so we need to remove it from the list before
 calling, and add passed skbs to a sublist afterwards.

Fixes: 17266ee9 ("net: ipv4: listified version of ip_rcv")
Reported-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NEdward Cree <ecree@solarflare.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>