MFP: Clear IGTK

The fourth and fifth keys are used as IGTK for management frame
protection. This patch clears these keys.

I have tested with linux kernel 2.6.31.2.

wpa_supplicant/wpa_supplicant.c

@@ -457,6 +457,10 @@ void wpa_clear_keys(struct wpa_supplicant *wpa_s, const u8 *addr)
 	wpa_drv_set_key(wpa_s, WPA_ALG_NONE, bcast, 1, 0, NULL, 0, NULL, 0);
 	wpa_drv_set_key(wpa_s, WPA_ALG_NONE, bcast, 2, 0, NULL, 0, NULL, 0);
 	wpa_drv_set_key(wpa_s, WPA_ALG_NONE, bcast, 3, 0, NULL, 0, NULL, 0);
+#ifdef CONFIG_IEEE80211W
+	wpa_drv_set_key(wpa_s, WPA_ALG_NONE, bcast, 4, 0, NULL, 0, NULL, 0);
+	wpa_drv_set_key(wpa_s, WPA_ALG_NONE, bcast, 5, 0, NULL, 0, NULL, 0);
+#endif /* CONFIG_IEEE80211W */
 	if (addr) {
 		wpa_drv_set_key(wpa_s, WPA_ALG_NONE, addr, 0, 0, NULL, 0, NULL,
 				0);