wlcore: use u8 instead of enum for bcn_filt_mode

Since we will export the conf structure as a file, we need to use well
defined types.  Instead of using enum, whose size may vary, use u8 for
bcn_filt_mode instead.
Signed-off-by: NLuciano Coelho <coelho@ti.com>

drivers/net/wireless/ti/wlcore/conf.h

@@ -824,7 +824,7 @@ struct conf_conn_settings {
 	 *
 	 * Range: CONF_BCN_FILT_MODE_*
 	 */
-	enum conf_bcn_filt_mode bcn_filt_mode;
+	u8 bcn_filt_mode;
 
 	/*
 	 * Configure Beacon filter pass-thru rules.