usb: fsl-mph-dr-of: 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/20230517230239.187727-61-u.kleine-koenig@pengutronix.deSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/fsl-mph-dr-of.c

@@ -265,10 +265,9 @@ static int __unregister_subdev(struct device *dev, void *d)
 	return 0;
 }
 
-static int fsl_usb2_mph_dr_of_remove(struct platform_device *ofdev)
+static void fsl_usb2_mph_dr_of_remove(struct platform_device *ofdev)
 {
 	device_for_each_child(&ofdev->dev, NULL, __unregister_subdev);
-	return 0;
 }
 
 #ifdef CONFIG_PPC_MPC512x
@@ -362,7 +361,7 @@ static struct platform_driver fsl_usb2_mph_dr_driver = {
 		.of_match_table = fsl_usb2_mph_dr_of_match,
 	},
 	.probe	= fsl_usb2_mph_dr_of_probe,
-	.remove	= fsl_usb2_mph_dr_of_remove,
+	.remove_new = fsl_usb2_mph_dr_of_remove,
 };
 
 module_platform_driver(fsl_usb2_mph_dr_driver);