can: gs_usb: GS_CAN_FLAG_OVERFLOW: make use of BIT()

This patch converts the driver to use BIT() to define flags.

Link: https://lore.kernel.org/all/20220309124132.291861-5-mkl@pengutronix.deSigned-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/usb/gs_usb.c

@@ -136,7 +136,7 @@ struct gs_device_bt_const {
 	__le32 brp_inc;
 } __packed;
 
-#define GS_CAN_FLAG_OVERFLOW 1
+#define GS_CAN_FLAG_OVERFLOW BIT(0)
 
 struct gs_host_frame {
 	u32 echo_id;