rpmsg: qcom_smd: 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 (mostly) ignored
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.

qcom_smd_remove() always returned zero, though that isn't completely
trivial to see. So explain that in a comment and convert to
.remove_new().
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230321154039.355098-4-u.kleine-koenig@pengutronix.de

drivers/rpmsg/qcom_smd.c

@@ -1579,15 +1579,13 @@ static int qcom_smd_remove_edge(struct device *dev, void *data)
  * Shut down all smd clients by making sure that each edge stops processing
  * events and scanning for new channels, then call destroy on the devices.
  */
-static int qcom_smd_remove(struct platform_device *pdev)
+static void qcom_smd_remove(struct platform_device *pdev)
 {
-	int ret;
-
-	ret = device_for_each_child(&pdev->dev, NULL, qcom_smd_remove_edge);
-	if (ret)
-		dev_warn(&pdev->dev, "can't remove smd device: %d\n", ret);
-
-	return ret;
+	/*
+	 * qcom_smd_remove_edge always returns zero, so there is no need to
+	 * check the return value of device_for_each_child.
+	 */
+	device_for_each_child(&pdev->dev, NULL, qcom_smd_remove_edge);
 }
 
 static const struct of_device_id qcom_smd_of_match[] = {
@@ -1598,7 +1596,7 @@ MODULE_DEVICE_TABLE(of, qcom_smd_of_match);
 
 static struct platform_driver qcom_smd_driver = {
 	.probe = qcom_smd_probe,
-	.remove = qcom_smd_remove,
+	.remove_new = qcom_smd_remove,
 	.driver = {
 		.name = "qcom-smd",
 		.of_match_table = qcom_smd_of_match,