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/mesh.c b/net/mac80211/mesh.c
index f76bc26..697ef67 100644
--- a/net/mac80211/mesh.c
+++ b/net/mac80211/mesh.c
@@ -397,7 +397,7 @@
 	put_unaligned(cpu_to_le32(sdata->u.sta.mesh_seqnum), &meshhdr->seqnum);
 	sdata->u.sta.mesh_seqnum++;
 
-	return 5;
+	return 6;
 }
 
 void ieee80211_mesh_init_sdata(struct ieee80211_sub_if_data *sdata)