mt76: connac: fix a theoretical NULL pointer dereference in mt76_connac_get_phy_mode

Even if it is not a real bug since mt76_connac_get_phy_mode runs just
for mt7921 where only STA is supported, fix a theoretical NULL pointer
dereference if new added modes do not support HE
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Felix Fietkau <nbd@nbd.name>

drivers/net/wireless/mediatek/mt76/mt76_connac_mcu.c

@@ -1179,7 +1179,7 @@ mt76_connac_get_phy_mode(struct mt76_phy *phy, struct ieee80211_vif *vif,
 		if (ht_cap->ht_supported)
 			mode |= PHY_MODE_GN;
 
-		if (he_cap->has_he)
+		if (he_cap && he_cap->has_he)
 			mode |= PHY_MODE_AX_24G;
 	} else if (band == NL80211_BAND_5GHZ || band == NL80211_BAND_6GHZ) {
 		mode |= PHY_MODE_A;
@@ -1190,7 +1190,7 @@ mt76_connac_get_phy_mode(struct mt76_phy *phy, struct ieee80211_vif *vif,
 		if (vht_cap->vht_supported)
 			mode |= PHY_MODE_AC;
 
-		if (he_cap->has_he) {
+		if (he_cap && he_cap->has_he) {
 			if (band == NL80211_BAND_6GHZ)
 				mode |= PHY_MODE_AX_6G;
 			else