drm/panel: samsung-atna33xc20: Don't call unprepare+disable at shutdown/remove

It's the responsibility of a correctly written DRM modeset driver to
call drm_atomic_helper_shutdown() at shutdown time and that should be
disabling / unpreparing the panel if needed. Panel drivers shouldn't
be calling these functions themselves.

A recent effort was made to fix as many DRM modeset drivers as
possible [1] [2] [3] and most drivers are fixed now.

A grep through mainline for compatible strings used by this driver
indicates that it is used by Qualcomm boards. The Qualcomm driver
appears to be correctly calling drm_atomic_helper_shutdown() so we can
remove the calls.

[1] https://lore.kernel.org/r/20230901234015.566018-1-dianders@chromium.org
[2] https://lore.kernel.org/r/20230901234202.566951-1-dianders@chromium.org
[3] https://lore.kernel.org/r/20230921192749.1542462-1-dianders@chromium.orgAcked-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Maxime Ripard <mripard@kernel.org>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240503143327.RFT.v2.25.Iaeacccf98e6cb729b8fc3a782725769cd66812ad@changeid

drivers/gpu/drm/panel/panel-samsung-atna33xc20.c

@@ -327,21 +327,10 @@ static void atana33xc20_remove(struct dp_aux_ep_device *aux_ep)
 	struct atana33xc20_panel *panel = dev_get_drvdata(dev);
 
 	drm_panel_remove(&panel->base);
-	drm_panel_disable(&panel->base);
-	drm_panel_unprepare(&panel->base);
 
 	drm_edid_free(panel->drm_edid);
 }
 
-static void atana33xc20_shutdown(struct dp_aux_ep_device *aux_ep)
-{
-	struct device *dev = &aux_ep->dev;
-	struct atana33xc20_panel *panel = dev_get_drvdata(dev);
-
-	drm_panel_disable(&panel->base);
-	drm_panel_unprepare(&panel->base);
-}
-
 static const struct of_device_id atana33xc20_dt_match[] = {
 	{ .compatible = "samsung,atna33xc20", },
 	{ /* sentinal */ }
@@ -362,7 +351,6 @@ static struct dp_aux_ep_driver atana33xc20_driver = {
 	},
 	.probe = atana33xc20_probe,
 	.remove = atana33xc20_remove,
-	.shutdown = atana33xc20_shutdown,
 };
 
 static int __init atana33xc20_init(void)