can: gs_usb: document GS_CAN_FEATURE_BERR_REPORTING

Document the new feature ("GS_CAN_FEATURE_BERR_REPORTING") that
indicates that the bus error reporting in the CAN controller can
switched on and off with the GS_CAN_MODE_BERR_REPORTING mode bit in
the GS_USB_BREQ_MODE control message.
Signed-off-by: Jeroen Hofstee <jhofstee@victronenergy.com>
Link: https://lore.kernel.org/all/20221019221016.1659260-5-mkl@pengutronix.deSigned-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/usb/gs_usb.c

@@ -134,6 +134,7 @@ struct gs_device_config {
 /* GS_CAN_FEATURE_REQ_USB_QUIRK_LPC546XX BIT(9) */
 /* GS_CAN_FEATURE_BT_CONST_EXT BIT(10) */
 /* GS_CAN_FEATURE_TERMINATION BIT(11) */
+#define GS_CAN_MODE_BERR_REPORTING BIT(12)
 
 struct gs_device_mode {
 	__le32 mode;
@@ -174,7 +175,8 @@ struct gs_device_termination_state {
 #define GS_CAN_FEATURE_REQ_USB_QUIRK_LPC546XX BIT(9)
 #define GS_CAN_FEATURE_BT_CONST_EXT BIT(10)
 #define GS_CAN_FEATURE_TERMINATION BIT(11)
-#define GS_CAN_FEATURE_MASK GENMASK(11, 0)
+#define GS_CAN_FEATURE_BERR_REPORTING BIT(12)
+#define GS_CAN_FEATURE_MASK GENMASK(12, 0)
 
 /* internal quirks - keep in GS_CAN_FEATURE space for now */