ieee80211_add_vhtcap
frm = ieee80211_add_vhtcap(frm, vap->iv_bss);
frm = ieee80211_add_vhtcap(frm, ni);
frm = ieee80211_add_vhtcap(frm, ni);
frm = ieee80211_add_vhtcap(frm, bss);
frm = ieee80211_add_vhtcap(frm, ni);
uint8_t * ieee80211_add_vhtcap(uint8_t *frm, struct ieee80211_node *);