mac80211: fix incorrect mesh header length

This should have been updated at the same time we were transitioning from 3 byte
to 4 byte mesh sequence number. Pointed out by Johannes Berg.

Signed-off-by: Luis Carlos Cobo <luisca@cozybit.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/net/mac80211/util.c b/net/mac80211/util.c
index cc9f715..24a465c 100644
--- a/net/mac80211/util.c
+++ b/net/mac80211/util.c
@@ -153,15 +153,15 @@
 	/* 7.1.3.5a.2 */
 	switch (ae) {
 	case 0:
-		return 5;
+		return 6;
 	case 1:
-		return 11;
+		return 12;
 	case 2:
-		return 17;
+		return 18;
 	case 3:
-		return 23;
+		return 24;
 	default:
-		return 5;
+		return 6;
 	}
 }