Share the same enum for MFP configuration

The three existing enums were already depending on using the same
values in couple of places and it is just simpler to standardize on
one of these to avoid need for mapping between different enums for
the exact same thing.

src/ap/wpa_auth.h

@@ -141,11 +141,7 @@ struct wpa_auth_config {
 	int wmm_enabled;
 	int okc;
 #ifdef CONFIG_IEEE80211W
-	enum {
-		WPA_NO_IEEE80211W = 0,
-		WPA_IEEE80211W_OPTIONAL = 1,
-		WPA_IEEE80211W_REQUIRED = 2
-	} ieee80211w;
+	enum mfp_options ieee80211w;
 #endif /* CONFIG_IEEE80211W */
 #ifdef CONFIG_IEEE80211R
 #define SSID_LEN 32