ath9k: Use HW HT capabilites properly

The commit "ath9k: Remove aggregation flags" changed how
nodes were being initialized. Use the HW HT cap bits
to initialize/de-initialize nodes, else we would be
accessing an uninitialized entry during a suspend/resume cycle,
resulting in a panic.
Reported-by: Justin P. Mattock <justinmattock@gmail.com>
Signed-off-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

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

@@ -640,7 +640,7 @@ static void ath_node_attach(struct ath_softc *sc, struct ieee80211_sta *sta,
 	an->sta = sta;
 	an->vif = vif;
 
-	if (sta->ht_cap.ht_supported) {
+	if (sc->sc_ah->caps.hw_caps & ATH9K_HW_CAP_HT) {
 		ath_tx_node_init(sc, an);
 		an->maxampdu = 1 << (IEEE80211_HT_MAX_AMPDU_FACTOR +
 				     sta->ht_cap.ampdu_factor);
@@ -659,7 +659,7 @@ static void ath_node_detach(struct ath_softc *sc, struct ieee80211_sta *sta)
 	an->sta = NULL;
 #endif
 
-	if (sta->ht_cap.ht_supported)
+	if (sc->sc_ah->caps.hw_caps & ATH9K_HW_CAP_HT)
 		ath_tx_node_cleanup(sc, an);
 }