drm/mipi-dsi: Make remove callback return void

All implementations return 0 and the return value of mipi_dsi_drv_remove()
is ignored anyhow.

So change the prototype of the remove function to return no value. This
way driver authors are not tempted to assume that passing an error to
the upper layer is a good idea. All drivers are adapted accordingly.
There is no intended change of behaviour.

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/20220708094922.1408248-4-u.kleine-koenig@pengutronix.de
diff --git a/drivers/gpu/drm/panel/panel-boe-tv101wum-nl6.c b/drivers/gpu/drm/panel/panel-boe-tv101wum-nl6.c
index 07f722f..857a2f0 100644
--- a/drivers/gpu/drm/panel/panel-boe-tv101wum-nl6.c
+++ b/drivers/gpu/drm/panel/panel-boe-tv101wum-nl6.c
@@ -1622,7 +1622,7 @@ static void boe_panel_shutdown(struct mipi_dsi_device *dsi)
 	drm_panel_unprepare(&boe->base);
 }
 
-static int boe_panel_remove(struct mipi_dsi_device *dsi)
+static void boe_panel_remove(struct mipi_dsi_device *dsi)
 {
 	struct boe_panel *boe = mipi_dsi_get_drvdata(dsi);
 	int ret;
@@ -1635,8 +1635,6 @@ static int boe_panel_remove(struct mipi_dsi_device *dsi)
 
 	if (boe->base.dev)
 		drm_panel_remove(&boe->base);
-
-	return 0;
 }
 
 static const struct of_device_id boe_of_match[] = {