mac80211: restrict assoc request VHT capabilities

In interoperability testing some APs showed bad behaviour
if some of the VHT capabilities of the station are better
than their own. Restrict the assoc request parameters
 - beamformee capabable,
 - RX STBC and
 - RX MCS set
to the subset that the AP can support.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/ieee80211_i.h

@@ -405,6 +405,8 @@ struct ieee80211_mgd_assoc_data {
 
 	u8 ap_ht_param;
 
+	struct ieee80211_vht_cap ap_vht_cap;
+
 	size_t ie_len;
 	u8 ie[];
 };