mac80211: fix maximum MTU

The maximum MTU shouldn't take the headers into account,
the maximum MSDU size is exactly the maximum MTU.
Signed-off-by: NT Krishna Chaitanya <chaitanyatk@posedge.com>
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>

net/mac80211/iface.c

@@ -207,17 +207,8 @@ void ieee80211_recalc_idle(struct ieee80211_local *local)
 
 static int ieee80211_change_mtu(struct net_device *dev, int new_mtu)
 {
-	int meshhdrlen;
-	struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
-
-	meshhdrlen = (sdata->vif.type == NL80211_IFTYPE_MESH_POINT) ? 5 : 0;
-
-	/* FIX: what would be proper limits for MTU?
-	 * This interface uses 802.3 frames. */
-	if (new_mtu < 256 ||
-	    new_mtu > IEEE80211_MAX_DATA_LEN - 24 - 6 - meshhdrlen) {
+	if (new_mtu < 256 || new_mtu > IEEE80211_MAX_DATA_LEN)
 		return -EINVAL;
-	}
 
 	dev->mtu = new_mtu;
 	return 0;