iwlwifi: clear rate control flags on non-HT packet

Clear the flags (most importantly, the IEEE80211_TX_RC_MCS flag)
when sending a non-HT packet so that the rate index can be properly treated.
This fixes the reporting of legacy rates in wireless-extensions for packets
sent after an HT packet.
Signed-off-by: NDaniel C Halperin <daniel.c.halperin@intel.com>
Signed-off-by: NReinette Chatre <reinette.chatre@intel.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

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

@@ -2546,6 +2546,7 @@ static void rs_get_rate(void *priv_r, struct ieee80211_sta *sta, void *priv_sta,
 			rate_idx = rate_lowest_index(sband, sta);
 		else if (sband->band == IEEE80211_BAND_5GHZ)
 			rate_idx -= IWL_FIRST_OFDM_RATE;
+		info->control.rates[0].flags = 0;
 	}
 	info->control.rates[0].idx = rate_idx;