xfrm: remove hdr_offset indirection

After previous patches all remaining users set the function pointer to
the same function: xfrm6_find_1stfragopt.

So remove this function pointer and call ip6_find_1stfragopt directly.

Reduces size of xfrm_type to 64 bytes on 64bit platforms.

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 1734339..10842d5 100644
--- a/net/xfrm/xfrm_output.c
+++ b/net/xfrm/xfrm_output.c
@@ -185,7 +185,7 @@ static int xfrm6_hdr_offset(struct xfrm_state *x, struct sk_buff *skb, u8 **prev
 		break;
 	}
 
-	return x->type->hdr_offset(x, skb, prevhdr);
+	return ip6_find_1stfragopt(skb, prevhdr);
 }
 
 /* Add encapsulation header.