ath9k: Handle chainmask for A9280

The default chainmask for AR9280 is 3, so handle that when setting
the supported MCS rates. Also, check for the HW supported chainmask
when choosing single/dual stream.
Signed-off-by: NSujith <Sujith.Manoharan@atheros.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath9k/main.c

@@ -876,6 +876,7 @@ static void setup_ht_cap(struct ath_softc *sc,
 	case 1:
 		ht_info->mcs.rx_mask[0] = 0xff;
 		break;
+	case 3:
 	case 5:
 	case 7:
 	default:

drivers/net/wireless/ath9k/rc.c

@@ -1359,7 +1359,7 @@ static void ath_rc_init(struct ath_softc *sc,
 
 	if (sta->ht_cap.ht_supported) {
 		ath_rc_priv->ht_cap = WLAN_RC_HT_FLAG;
-		if (sc->sc_tx_chainmask != 1)
+		if (sc->sc_ah->ah_caps.tx_chainmask != 1)
 			ath_rc_priv->ht_cap |= WLAN_RC_DS_FLAG;
 		if (sta->ht_cap.cap & IEEE80211_HT_CAP_SUP_WIDTH_20_40)
 			ath_rc_priv->ht_cap |= WLAN_RC_40_FLAG;