drm/panel: simple: Make panel_simple_remove() return void

panel_simple_remove() returns zero unconditionally. Make it return no value
instead making more obvious what happens in the callers.

This is a preparation for making platform and mipi-dsi remove callbacks
return void.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20220708094922.1408248-2-u.kleine-koenig@pengutronix.de

drivers/gpu/drm/panel/panel-simple.c

@@ -696,7 +696,7 @@ static int panel_simple_probe(struct device *dev, const struct panel_desc *desc)
 	return err;
 }
 
-static int panel_simple_remove(struct device *dev)
+static void panel_simple_remove(struct device *dev)
 {
 	struct panel_simple *panel = dev_get_drvdata(dev);
 
@@ -708,8 +708,6 @@ static int panel_simple_remove(struct device *dev)
 	pm_runtime_disable(dev);
 	if (panel->ddc)
 		put_device(&panel->ddc->dev);
-
-	return 0;
 }
 
 static void panel_simple_shutdown(struct device *dev)
@@ -4273,7 +4271,9 @@ static int panel_simple_platform_probe(struct platform_device *pdev)
 
 static int panel_simple_platform_remove(struct platform_device *pdev)
 {
-	return panel_simple_remove(&pdev->dev);
+	panel_simple_remove(&pdev->dev);
+
+	return 0;
 }
 
 static void panel_simple_platform_shutdown(struct platform_device *pdev)
@@ -4574,7 +4574,9 @@ static int panel_simple_dsi_remove(struct mipi_dsi_device *dsi)
 	if (err < 0)
 		dev_err(&dsi->dev, "failed to detach from DSI host: %d\n", err);
 
-	return panel_simple_remove(&dsi->dev);
+	panel_simple_remove(&dsi->dev);
+
+	return 0;
 }
 
 static void panel_simple_dsi_shutdown(struct mipi_dsi_device *dsi)