gpio: grgpio: Fix device removing

If a platform device's remove callback returns non-zero, the device core
emits a warning and still removes the device and calls the devm cleanup
callbacks.

So it's not save to not unregister the gpiochip because on the next request
to a GPIO the driver accesses kfree()'d memory. Also if an IRQ triggers,
the freed memory is accessed.

Instead rely on the GPIO framework to ensure that after gpiochip_remove()
all GPIOs are freed and so the corresponding IRQs are unmapped.

This is a preparation for making platform remove callbacks return void.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>

drivers/gpio/gpio-grgpio.c

@@ -434,25 +434,13 @@ static int grgpio_probe(struct platform_device *ofdev)
 static int grgpio_remove(struct platform_device *ofdev)
 {
 	struct grgpio_priv *priv = platform_get_drvdata(ofdev);
-	int i;
-	int ret = 0;
-
-	if (priv->domain) {
-		for (i = 0; i < GRGPIO_MAX_NGPIO; i++) {
-			if (priv->uirqs[i].refcnt != 0) {
-				ret = -EBUSY;
-				goto out;
-			}
-		}
-	}
 
 	gpiochip_remove(&priv->gc);
 
 	if (priv->domain)
 		irq_domain_remove(priv->domain);
 
-out:
-	return ret;
+	return 0;
 }
 
 static const struct of_device_id grgpio_match[] = {