wifi: mac80211: don't add VHT capa on links without them

When a link doesn't have VHT capability, before the rework
we'd have set IEEE80211_CONN_DISABLE_VHT, but now with the
linear progression of 'mode', we no longer have that. Add
an explicit check for VHT being supported, so we don't add
a zeroed VHT capabilities element where it shouldn't be.

Fixes: 310c8387 ("wifi: mac80211: clean up connection process")
Reviewed-by: Miriam Rachel Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://msgid.link/20240228094207.bfe4283bcde7.Ib70a558bc6bdbcec3d9e663079229dfcc2493682@changeidSigned-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/mlme.c

@@ -1319,7 +1319,8 @@ static size_t ieee80211_assoc_link_elems(struct ieee80211_sub_if_data *sdata,
 						offset);
 
 	if (sband->band != NL80211_BAND_6GHZ &&
-	    assoc_data->link[link_id].conn.mode >= IEEE80211_CONN_MODE_VHT) {
+	    assoc_data->link[link_id].conn.mode >= IEEE80211_CONN_MODE_VHT &&
+	    sband->vht_cap.vht_supported) {
 		bool mu_mimo_owner =
 			ieee80211_add_vht_ie(sdata, skb, sband,
 					     &assoc_data->link[link_id].ap_vht_cap,