iwlwifi: check IEEE80211_TX_STAT_AMPDU for agg pkt

when perform rate scaling, in tx status function, checking for
IEEE80211_TX_STAT_AMPDU flag instead of IEEE_TX_CTL_AMPDU flag to perform
AMPDU rate scaling operation.

IEEE80211_TX_CTL_AMPDU was set by mac80211 for aggregation pkt. But when
iwlwifi receive the tx status reply, it reset the flag to following
	info->flags = IEEE80211_TX_STAT_ACK;
	info->flags |= IEEE80211_TX_STAT_AMPDU;
it causes the rate-scaling to not work for aggregation pkt if we checking
for IEEE80211_TX_CTL_AMPDU flag.

Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/iwlwifi/iwl-agn-rs.c

@@ -916,7 +916,7 @@ static void rs_tx_status(void *priv_r, struct ieee80211_supported_band *sband,
 			tpt = search_tbl->expected_tpt[rs_index];
 		else
 			tpt = 0;
-		if (info->flags & IEEE80211_TX_CTL_AMPDU)
+		if (info->flags & IEEE80211_TX_STAT_AMPDU)
 			rs_collect_tx_data(search_win, rs_index, tpt,
 					   info->status.ampdu_ack_len,
 					   info->status.ampdu_ack_map);
@@ -932,7 +932,7 @@ static void rs_tx_status(void *priv_r, struct ieee80211_supported_band *sband,
 			tpt = curr_tbl->expected_tpt[rs_index];
 		else
 			tpt = 0;
-		if (info->flags & IEEE80211_TX_CTL_AMPDU)
+		if (info->flags & IEEE80211_TX_STAT_AMPDU)
 			rs_collect_tx_data(window, rs_index, tpt,
 					   info->status.ampdu_ack_len,
 					   info->status.ampdu_ack_map);
@@ -944,7 +944,7 @@ static void rs_tx_status(void *priv_r, struct ieee80211_supported_band *sband,
 	/* If not searching for new mode, increment success/failed counter
 	 * ... these help determine when to start searching again */
 	if (lq_sta->stay_in_tbl) {
-		if (info->flags & IEEE80211_TX_CTL_AMPDU) {
+		if (info->flags & IEEE80211_TX_STAT_AMPDU) {
 			lq_sta->total_success += info->status.ampdu_ack_map;
 			lq_sta->total_failed +=
 			     (info->status.ampdu_ack_len - info->status.ampdu_ack_map);