FT: Replace inter-AP protocol with use of OUI Extended Ethertype

Replace the previously used extension of IEEE 802.11 managed Ethertype
89-0d (originally added for Remote Request/Response in IEEE 802.11r)
with Ethertype 88-b7 (OUI Extended EtherType) for FT inter-AP
communication. The new design uses a more properly assigned identifier
for the messages.

This assigns the OUI 00:13:74 vendor-specific subtype 0x0001 for the new
hostapd AP-to-AP communication purposes. Subtypes 1 (PULL), 2 (RESP),
and 3 (PUSH) are also assigned in this commit for the R0KH-R1KH
protocol.

This breaks backward compatibility, i.e., hostapd needs to be updated on
all APs at the same time to allow FT to remain functional.

Signed-off-by: Michael Braun <michael-dev@fami-braun.de>

src/utils/common.h

@@ -331,6 +331,9 @@ static inline void WPA_PUT_LE64(u8 *a, u64 val)
 #ifndef ETH_P_RRB
 #define ETH_P_RRB 0x890D
 #endif /* ETH_P_RRB */
+#ifndef ETH_P_OUI
+#define ETH_P_OUI 0x88B7
+#endif /* ETH_P_OUI */
 
 
 #ifdef __GNUC__