can: kvaser_usb: Ignore CMD_FLUSH_QUEUE_REPLY messages

To avoid kernel warning "Unhandled message (68)", ignore the
CMD_FLUSH_QUEUE_REPLY message for now.

As of Leaf v2 firmware version v4.1.844 (2017-02-15), flush tx queue is
synchronous. There is a capability bit indicating whether flushing tx
queue is synchronous or asynchronous.

A proper solution would be to query the device for capabilities. If the
synchronous tx flush capability bit is set, we should wait for
CMD_FLUSH_QUEUE_REPLY message, while flushing the tx queue.

Signed-off-by: Jimmy Assarsson <jimmyassarsson@gmail.com>
Cc: linux-stable <stable@vger.kernel.org>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/usb/kvaser_usb.c

@@ -137,6 +137,7 @@ static inline bool kvaser_is_usbcan(const struct usb_device_id *id)
 #define CMD_RESET_ERROR_COUNTER		49
 #define CMD_TX_ACKNOWLEDGE		50
 #define CMD_CAN_ERROR_EVENT		51
+#define CMD_FLUSH_QUEUE_REPLY		68
 
 #define CMD_LEAF_USB_THROTTLE		77
 #define CMD_LEAF_LOG_MESSAGE		106
@@ -1301,6 +1302,11 @@ static void kvaser_usb_handle_message(const struct kvaser_usb *dev,
 			goto warn;
 		break;
 
+	case CMD_FLUSH_QUEUE_REPLY:
+		if (dev->family != KVASER_LEAF)
+			goto warn;
+		break;
+
 	default:
 warn:		dev_warn(dev->udev->dev.parent,
 			 "Unhandled message (%d)\n", msg->id);