USB: usbip: convert platform driver to use dev_groups

Platform drivers now have the option to have the platform core create
and remove any needed sysfs attribute files. So take advantage of that
and do not register "by hand" any sysfs files.

Cc: Valentina Manea <[e-mail]>
Acked-by: Shuah Khan <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/usb/usbip/vudc.h

···
 	struct list_head dev_entry;
 };
 
-extern const struct attribute_group vudc_attr_group;
+extern const struct attribute_group *vudc_groups[];
 
 /* visible everywhere */
 

drivers/usb/usbip/vudc_dev.c

···
 	if (ret < 0)
 		goto err_add_udc;
 
-	ret = sysfs_create_group(&pdev->dev.kobj, &vudc_attr_group);
-	if (ret) {
-		dev_err(&udc->pdev->dev, "create sysfs files\n");
-		goto err_sysfs;
-	}
-
 	platform_set_drvdata(pdev, udc);
 
 	return ret;
 
-err_sysfs:
-	usb_del_gadget_udc(&udc->gadget);
 err_add_udc:
 	cleanup_vudc_hw(udc);
 err_init_vudc_hw:
···
 {
 	struct vudc *udc = platform_get_drvdata(pdev);
 
-	sysfs_remove_group(&pdev->dev.kobj, &vudc_attr_group);
 	usb_del_gadget_udc(&udc->gadget);
 	cleanup_vudc_hw(udc);
 	kfree(udc);

drivers/usb/usbip/vudc_main.c

···
 	.remove		= vudc_remove,
 	.driver		= {
 		.name	= GADGET_NAME,
+		.dev_groups = vudc_groups,
 	},
 };
 

drivers/usb/usbip/vudc_sysfs.c

···
 	NULL,
 };
 
-const struct attribute_group vudc_attr_group = {
+static const struct attribute_group vudc_attr_group = {
 	.attrs = dev_attrs,
 	.bin_attrs = dev_bin_attrs,
+};
+
+const struct attribute_group *vudc_groups[] = {
+	&vudc_attr_group,
+	NULL,
 };