serial: atmel: 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>
Reviewed-by: Claudiu Beznea <claudiu.beznea@tuxon.dev>
Acked-by: Richard Genoud <richard.genoud@gmail.com>
Link: https://lore.kernel.org/r/20231110152927.70601-9-u.kleine-koenig@pengutronix.deSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/atmel_serial.c

@@ -3001,7 +3001,7 @@ static int atmel_serial_probe(struct platform_device *pdev)
  * protocol that needs bitbanging on IO lines, but use the regular serial
  * port in the normal case.
  */
-static int atmel_serial_remove(struct platform_device *pdev)
+static void atmel_serial_remove(struct platform_device *pdev)
 {
 	struct uart_port *port = platform_get_drvdata(pdev);
 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
@@ -3020,8 +3020,6 @@ static int atmel_serial_remove(struct platform_device *pdev)
 	clear_bit(port->line, atmel_ports_in_use);
 
 	pdev->dev.of_node = NULL;
-
-	return 0;
 }
 
 static SIMPLE_DEV_PM_OPS(atmel_serial_pm_ops, atmel_serial_suspend,
@@ -3029,7 +3027,7 @@ static SIMPLE_DEV_PM_OPS(atmel_serial_pm_ops, atmel_serial_suspend,
 
 static struct platform_driver atmel_serial_driver = {
 	.probe		= atmel_serial_probe,
-	.remove		= atmel_serial_remove,
+	.remove_new	= atmel_serial_remove,
 	.driver		= {
 		.name			= "atmel_usart_serial",
 		.of_match_table		= of_match_ptr(atmel_serial_dt_ids),