mac80211: use skb list for fragments

We are currently linking the skbs by using skb->next
directly. This works, but the preferred way is to use
a struct sk_buff_head instead. That also prepares for
passing that to drivers directly.

While at it I noticed we calculate the duration for
fragments twice -- remove one of them.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

net/mac80211/wep.c

@@ -330,13 +330,12 @@ ieee80211_crypto_wep_encrypt(struct ieee80211_tx_data *tx)
 
 	ieee80211_tx_set_protected(tx);
 
-	skb = tx->skb;
-	do {
+	skb_queue_walk(&tx->skbs, skb) {
 		if (wep_encrypt_skb(tx, skb) < 0) {
 			I802_DEBUG_INC(tx->local->tx_handlers_drop_wep);
 			return TX_DROP;
 		}
-	} while ((skb = skb->next));
+	}
 
 	return TX_CONTINUE;
 }