implement WPA2 Stations Key handling

Implement the required support for extrace the cipher
suite settings from the the RS Information Element and
set the station key based on the 802.11 Station Key
CAPWAP message element.

Group Key update handling is currently not implemented nor is
Station Key update handling.

src/wtp/kmod/capwap.h

@@ -50,12 +50,15 @@ union capwap_addr {
 	struct sockaddr_storage ss;
 };
 
+#define STA_FLAG_AKM_ONLY	0x0001
+
 struct sc_station {
 	struct hlist_node station_list;
 
 	uint8_t radioid;
 	uint8_t mac[ETH_ALEN];
 	uint8_t wlanid;
+	uint32_t flags;
 
 	struct rcu_head rcu_head;
 };