mac80211: make ieee80211_find_sta per virtual interface

Since we have a TODO item to make all station
management dependent on virtual interfaces, I
figured I'd start with pushing such a change
to drivers before more drivers start using the
ieee80211_find_sta() API with a hw pointer and
cause us grief later on.

For now continue exporting the old API in form
of ieee80211_find_sta_by_hw(), but discourage
its use strongly.

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

drivers/net/wireless/ath/ath9k/recv.c

@@ -202,7 +202,8 @@ static int ath_rx_prepare(struct sk_buff *skb, struct ath_desc *ds,
 	}
 
 	rcu_read_lock();
-	sta = ieee80211_find_sta(sc->hw, hdr->addr2);
+	/* XXX: use ieee80211_find_sta! */
+	sta = ieee80211_find_sta_by_hw(sc->hw, hdr->addr2);
 	if (sta) {
 		an = (struct ath_node *) sta->drv_priv;
 		if (ds->ds_rxstat.rs_rssi != ATH9K_RSSI_BAD &&