char: xillybus: fix a refcount leak in cleanup_dev()

usb_get_dev is called in xillyusb_probe. So it is better to call
usb_put_dev before xdev is released.

Acked-by: Eli Billauer <eli.billauer@gmail.com>
Signed-off-by: Hangyu Hua <hbh25y@gmail.com>
Link: https://lore.kernel.org/r/20220406075703.23464-1-hbh25y@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/char/xillybus/xillyusb.c

@@ -549,6 +549,7 @@ static void cleanup_dev(struct kref *kref)
 	if (xdev->workq)
 		destroy_workqueue(xdev->workq);
 
+	usb_put_dev(xdev->udev);
 	kfree(xdev->channels); /* Argument may be NULL, and that's fine */
 	kfree(xdev);
 }