mac80211/rt2x00: add ieee80211_tx_status_ni()

All rt2x00 drivers except rt2800pci call ieee80211_tx_status() from
a workqueue, which causes "NOHZ: local_softirq_pending 08" messages.

To fix it, add ieee80211_tx_status_ni() similar to ieee80211_rx_ni()
which can be called from process context, and call it from
rt2x00lib_txdone().  For the rt2800pci special case a driver
flag is introduced.

Signed-off-by: Johannes Stezenbach <js@sig21.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/rt2x00/rt2x00dev.c b/drivers/net/wireless/rt2x00/rt2x00dev.c
index c879f9a..bd3afc9 100644
--- a/drivers/net/wireless/rt2x00/rt2x00dev.c
+++ b/drivers/net/wireless/rt2x00/rt2x00dev.c
@@ -379,9 +379,12 @@
 	 * through a mac80211 library call (RTS/CTS) then we should not
 	 * send the status report back.
 	 */
-	if (!(skbdesc_flags & SKBDESC_NOT_MAC80211))
-		ieee80211_tx_status(rt2x00dev->hw, entry->skb);
-	else
+	if (!(skbdesc_flags & SKBDESC_NOT_MAC80211)) {
+		if (test_bit(DRIVER_REQUIRE_TASKLET_CONTEXT, &rt2x00dev->flags))
+			ieee80211_tx_status(rt2x00dev->hw, entry->skb);
+		else
+			ieee80211_tx_status_ni(rt2x00dev->hw, entry->skb);
+	} else
 		dev_kfree_skb_any(entry->skb);
 
 	/*