usb: gadget/dummy_hcd: Convert to platform remove callback returning void

The .remove() callback for a platform driver returns an int which makes
many driver authors wrongly assume it's possible to do error handling by
returning an error code. However the value returned is ignored (apart from
emitting a warning) and this typically results in resource leaks. To improve
here there is a quest to make the remove callback return void. In the first
step of this quest all drivers are converted to .remove_new() which already
returns void. Eventually after all drivers are converted, .remove_new() is
renamed to .remove().

Trivially convert this driver from always returning zero in the remove
callback to the void returning variant.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20230517230239.187727-30-u.kleine-koenig@pengutronix.deSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/gadget/udc/dummy_hcd.c

@@ -1108,13 +1108,12 @@ static int dummy_udc_probe(struct platform_device *pdev)
 	return rc;
 }
 
-static int dummy_udc_remove(struct platform_device *pdev)
+static void dummy_udc_remove(struct platform_device *pdev)
 {
 	struct dummy	*dum = platform_get_drvdata(pdev);
 
 	device_remove_file(&dum->gadget.dev, &dev_attr_function);
 	usb_del_gadget_udc(&dum->gadget);
-	return 0;
 }
 
 static void dummy_udc_pm(struct dummy *dum, struct dummy_hcd *dum_hcd,
@@ -1150,7 +1149,7 @@ static int dummy_udc_resume(struct platform_device *pdev)
 
 static struct platform_driver dummy_udc_driver = {
 	.probe		= dummy_udc_probe,
-	.remove		= dummy_udc_remove,
+	.remove_new	= dummy_udc_remove,
 	.suspend	= dummy_udc_suspend,
 	.resume		= dummy_udc_resume,
 	.driver		= {
@@ -2701,7 +2700,7 @@ static int dummy_hcd_probe(struct platform_device *pdev)
 	return retval;
 }
 
-static int dummy_hcd_remove(struct platform_device *pdev)
+static void dummy_hcd_remove(struct platform_device *pdev)
 {
 	struct dummy		*dum;
 
@@ -2717,8 +2716,6 @@ static int dummy_hcd_remove(struct platform_device *pdev)
 
 	dum->hs_hcd = NULL;
 	dum->ss_hcd = NULL;
-
-	return 0;
 }
 
 static int dummy_hcd_suspend(struct platform_device *pdev, pm_message_t state)
@@ -2753,7 +2750,7 @@ static int dummy_hcd_resume(struct platform_device *pdev)
 
 static struct platform_driver dummy_hcd_driver = {
 	.probe		= dummy_hcd_probe,
-	.remove		= dummy_hcd_remove,
+	.remove_new	= dummy_hcd_remove,
 	.suspend	= dummy_hcd_suspend,
 	.resume		= dummy_hcd_resume,
 	.driver		= {