[TCP]: Use TCPOLEN_TSTAMP_ALIGNED macro instead of magic number.

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 3b65754..34e004b 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -653,7 +653,7 @@
 	int tot_len = sizeof(struct tcphdr);
 
 	if (ts)
-		tot_len += 3*4;
+		tot_len += TCPOLEN_TSTAMP_ALIGNED;
 
 	buff = alloc_skb(MAX_HEADER + sizeof(struct ipv6hdr) + tot_len,
 			 GFP_ATOMIC);