tcp: add init_seq method to tcp_request_sock_ops

More work in preparation of unifying tcp_v4_conn_request and
tcp_v6_conn_request: indirect the init sequence calls via the
tcp_request_sock_ops.

Signed-off-by: Octavian Purdila <octavian.purdila@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 59fcc59..8cacf0d 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1608,6 +1608,7 @@
 	struct dst_entry *(*route_req)(struct sock *sk, struct flowi *fl,
 				       const struct request_sock *req,
 				       bool *strict);
+	__u32 (*init_seq)(const struct sk_buff *skb);
 };
 
 #ifdef CONFIG_SYN_COOKIES