ath9k: Enable SGI correctly

Set the driver specific SGI flag based on the station's
HT capabilities, otherwise rate control uses the wrong rate.
Signed-off-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/ath9k/rc.c

@@ -1222,11 +1222,14 @@ static u8 ath_rc_build_ht_caps(struct ath_softc *sc, struct ieee80211_sta *sta)
 			caps |= WLAN_RC_TS_FLAG | WLAN_RC_DS_FLAG;
 		else if (sta->ht_cap.mcs.rx_mask[1])
 			caps |= WLAN_RC_DS_FLAG;
-		if (sta->ht_cap.cap & IEEE80211_HT_CAP_SUP_WIDTH_20_40)
+		if (sta->ht_cap.cap & IEEE80211_HT_CAP_SUP_WIDTH_20_40) {
 			caps |= WLAN_RC_40_FLAG;
-		if (sta->ht_cap.cap & IEEE80211_HT_CAP_SGI_40 ||
-		    sta->ht_cap.cap & IEEE80211_HT_CAP_SGI_20)
-			caps |= WLAN_RC_SGI_FLAG;
+			if (sta->ht_cap.cap & IEEE80211_HT_CAP_SGI_40)
+				caps |= WLAN_RC_SGI_FLAG;
+		} else {
+			if (sta->ht_cap.cap & IEEE80211_HT_CAP_SGI_20)
+				caps |= WLAN_RC_SGI_FLAG;
+		}
 	}
 
 	return caps;