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/drivers/driver.h

@@ -356,11 +356,7 @@ struct wpa_driver_associate_params {
 	/**
 	 * mgmt_frame_protection - IEEE 802.11w management frame protection
 	 */
-	enum {
-		NO_MGMT_FRAME_PROTECTION,
-		MGMT_FRAME_PROTECTION_OPTIONAL,
-		MGMT_FRAME_PROTECTION_REQUIRED
-	} mgmt_frame_protection;
+	enum mfp_options mgmt_frame_protection;
 
 	/**
 	 * ft_ies - IEEE 802.11r / FT information elements