mac80211: make tx() operation return void

The return value of the tx operation is commonly
misused by drivers, leading to errors. All drivers
will drop frames if they fail to TX the frame, and
they must also properly manage the queues (if they
didn't, mac80211 would already warn).

Removing the ability for drivers to return a BUSY
value also allows significant cleanups of the TX
TX handling code in mac80211.

Note that this also fixes a bug in ath9k_htc, the
old "return -1" there was wrong.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Tested-by: Sedat Dilek <sedat.dilek@googlemail.com> [ath5k]
Acked-by: Gertjan van Wingerde <gwingerde@gmail.com> [rt2x00]
Acked-by: Larry Finger <Larry.Finger@lwfinger.net> [b43, rtl8187, rtlwifi]
Acked-by: Luciano Coelho <coelho@ti.com> [wl12xx]
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/iwlegacy/iwl3945-base.c b/drivers/net/wireless/iwlegacy/iwl3945-base.c
index ef94d16..a6af981 100644
--- a/drivers/net/wireless/iwlegacy/iwl3945-base.c
+++ b/drivers/net/wireless/iwlegacy/iwl3945-base.c
@@ -3170,7 +3170,7 @@
 	IWL_DEBUG_MAC80211(priv, "leave\n");
 }
 
-static int iwl3945_mac_tx(struct ieee80211_hw *hw, struct sk_buff *skb)
+static void iwl3945_mac_tx(struct ieee80211_hw *hw, struct sk_buff *skb)
 {
 	struct iwl_priv *priv = hw->priv;
 
@@ -3183,7 +3183,6 @@
 		dev_kfree_skb_any(skb);
 
 	IWL_DEBUG_MAC80211(priv, "leave\n");
-	return NETDEV_TX_OK;
 }
 
 void iwl3945_config_ap(struct iwl_priv *priv)