can: m_can: 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/20230512212725.143824-12-u.kleine-koenig@pengutronix.deSigned-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/m_can/m_can_platform.c

@@ -164,7 +164,7 @@ static __maybe_unused int m_can_resume(struct device *dev)
 	return m_can_class_resume(dev);
 }
 
-static int m_can_plat_remove(struct platform_device *pdev)
+static void m_can_plat_remove(struct platform_device *pdev)
 {
 	struct m_can_plat_priv *priv = platform_get_drvdata(pdev);
 	struct m_can_classdev *mcan_class = &priv->cdev;
@@ -172,8 +172,6 @@ static int m_can_plat_remove(struct platform_device *pdev)
 	m_can_class_unregister(mcan_class);
 
 	m_can_class_free_dev(mcan_class->net);
-
-	return 0;
 }
 
 static int __maybe_unused m_can_runtime_suspend(struct device *dev)
@@ -223,7 +221,7 @@ static struct platform_driver m_can_plat_driver = {
 		.pm     = &m_can_pmops,
 	},
 	.probe = m_can_plat_probe,
-	.remove = m_can_plat_remove,
+	.remove_new = m_can_plat_remove,
 };
 
 module_platform_driver(m_can_plat_driver);