rt2x00: Improve cooperation between rt2800pci and minstrel

In order to lower the impact of probe rates don't send a frame as AMPDU
if the rate control algorithm sets IEEE80211_TX_CTL_RATE_CTRL_PROBE.
Otherwise a whole aggregate would be send with a probe rate which might
lead to numerous retries.
Signed-off-by: Helmut Schaa <helmut.schaa@googlemail.com>
Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/rt2x00/rt2x00ht.c

@@ -73,9 +73,11 @@ void rt2x00ht_create_tx_descriptor(struct queue_entry *entry,
 
 
 	/*
-	 * Convert flags
+	 * This frame is eligible for an AMPDU, however, don't aggregate
+	 * frames that are intended to probe a specific tx rate.
 	 */
-	if (tx_info->flags & IEEE80211_TX_CTL_AMPDU)
+	if (tx_info->flags & IEEE80211_TX_CTL_AMPDU &&
+	    !(tx_info->flags & IEEE80211_TX_CTL_RATE_CTRL_PROBE))
 		__set_bit(ENTRY_TXD_HT_AMPDU, &txdesc->flags);
 
 	/*