xfrm: remove output_finish indirection from xfrm_state_afinfo

There are only two implementaions, one for ipv4 and one for ipv6.

Both are almost identical, they clear skb->cb[], set the TRANSFORMED flag
in IP(6)CB and then call the common xfrm_output() function.

By placing the IPCB handling into the common function, we avoid the need
for the output_finish indirection as the output functions can simply
use xfrm_output().

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
diff --git a/net/xfrm/xfrm_output.c b/net/xfrm/xfrm_output.c
index 3a646df..9c43b8d 100644
--- a/net/xfrm/xfrm_output.c
+++ b/net/xfrm/xfrm_output.c
@@ -571,6 +571,22 @@ int xfrm_output(struct sock *sk, struct sk_buff *skb)
 	struct xfrm_state *x = skb_dst(skb)->xfrm;
 	int err;
 
+	switch (x->outer_mode.family) {
+	case AF_INET:
+		memset(IPCB(skb), 0, sizeof(*IPCB(skb)));
+#ifdef CONFIG_NETFILTER
+		IPCB(skb)->flags |= IPSKB_XFRM_TRANSFORMED;
+#endif
+		break;
+	case AF_INET6:
+		memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
+
+#ifdef CONFIG_NETFILTER
+		IP6CB(skb)->flags |= IP6SKB_XFRM_TRANSFORMED;
+#endif
+		break;
+	}
+
 	secpath_reset(skb);
 
 	if (xfrm_dev_offload_ok(skb, x)) {