tcp: remove unnecessary assignment.

This variable i is overwritten to 0 by following code
Signed-off-by: NLi RongQing <roy.qing.li@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/tcp_fastopen.c

@@ -115,7 +115,7 @@ static bool tcp_fastopen_cookie_gen(struct request_sock *req,
 
 		if (__tcp_fastopen_cookie_gen(&ip6h->saddr, &tmp)) {
 			struct in6_addr *buf = (struct in6_addr *) tmp.val;
-			int i = 4;
+			int i;
 
 			for (i = 0; i < 4; i++)
 				buf->s6_addr32[i] ^= ip6h->daddr.s6_addr32[i];