mailbox: imx: 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() will be 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>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>

Author: Uwe Kleine-König

drivers/mailbox/imx-mailbox.c

@@ -903,13 +903,11 @@ static int imx_mu_probe(struct platform_device *pdev)
 	return ret;
 }
 
-static int imx_mu_remove(struct platform_device *pdev)
+static void imx_mu_remove(struct platform_device *pdev)
 {
 	struct imx_mu_priv *priv = platform_get_drvdata(pdev);
 
 	pm_runtime_disable(priv->dev);
-
-	return 0;
 }
 
 static const struct imx_mu_dcfg imx_mu_cfg_imx6sx = {
@@ -1070,7 +1068,7 @@ static const struct dev_pm_ops imx_mu_pm_ops = {
 
 static struct platform_driver imx_mu_driver = {
 	.probe		= imx_mu_probe,
-	.remove		= imx_mu_remove,
+	.remove_new	= imx_mu_remove,
 	.driver = {
 		.name	= "imx_mu",
 		.of_match_table = imx_mu_dt_ids,