net: ipv4: Fix wrong type conversion from hint to rt in ip_route_use_hint()

We can't cast sk_buff to rtable by (struct rtable *)hint. Use skb_rtable().

Fixes: 02b24941

 ("ipv4: use dst hint for ipv4 list receive")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>