hostapd: Make VHT IE struct more expressive

The VHT IE struct just has an opaque 8-byte array for the MCS
set, make it more expressive by explicitly naming the pieces.

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

src/ap/ieee802_11_vht.c

@@ -38,7 +38,7 @@ u8 * hostapd_eid_vht_capabilities(struct hostapd_data *hapd, u8 *eid)
 		hapd->iface->current_mode->vht_capab);
 
 	/* Supported MCS set comes from hw */
-	os_memcpy(cap->vht_supported_mcs_set,
+	os_memcpy(&cap->vht_supported_mcs_set,
 	          hapd->iface->current_mode->vht_mcs_set, 8);
 
 	pos += sizeof(*cap);

src/common/ieee802_11_defs.h

@@ -579,7 +579,12 @@ struct ieee80211_ht_operation {
 
 struct ieee80211_vht_capabilities {
 	le32 vht_capabilities_info;
-	u8 vht_supported_mcs_set[8];
+	struct {
+		le16 rx_map;
+		le16 rx_highest;
+		le16 tx_map;
+		le16 tx_highest;
+	} vht_supported_mcs_set;
 } STRUCT_PACKED;
 
 struct ieee80211_vht_operation {