tcp: replace ehash_size by ehash_mask

Storing the mask (size - 1) instead of the size allows fast path to be
a bit faster.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/inet6_hashtables.c b/net/ipv6/inet6_hashtables.c
index 1bcc343..874aed8 100644
--- a/net/ipv6/inet6_hashtables.c
+++ b/net/ipv6/inet6_hashtables.c
@@ -73,7 +73,7 @@
 	 * have wildcards anyways.
 	 */
 	unsigned int hash = inet6_ehashfn(net, daddr, hnum, saddr, sport);
-	unsigned int slot = hash & (hashinfo->ehash_size - 1);
+	unsigned int slot = hash & hashinfo->ehash_mask;
 	struct inet_ehash_bucket *head = &hashinfo->ehash[slot];