net: use inet6_iif instead of IP6CB()->iif

Signed-off-by: Duan Jiong <duanj.fnst@cn.fujitsu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index c6941a1..4836af8 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -472,7 +472,7 @@
 			sin6->sin6_addr = ipv6_hdr(skb)->saddr;
 			sin6->sin6_scope_id =
 				ipv6_iface_scope_id(&sin6->sin6_addr,
-						    IP6CB(skb)->iif);
+						    inet6_iif(skb));
 		}
 		*addr_len = sizeof(*sin6);
 	}