drm/panel: kingdisplay-kd097d04: 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 Rockchip boards. The Rockchip driver
appear to be correctly calling drm_atomic_helper_shutdown() so we can
remove the calls.

[1] https://lore.kernel.org/r/[e-mail]
[2] https://lore.kernel.org/r/[e-mail]
[3] https://lore.kernel.org/r/[e-mail]

Cc: Brian Norris <[e-mail]>
Cc: Chris Zhong <[e-mail]>
Cc: Nickey Yang <[e-mail]>
Acked-by: Linus Walleij <[e-mail]>
Acked-by: Maxime Ripard <[e-mail]>
Reviewed-by: Heiko Stuebner <[e-mail]>
Signed-off-by: Douglas Anderson <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/20240503143327.RFT.v2.13.I6c7c84b1560dd374f6e7e8dc50f419a870d31d31@changeid

drivers/gpu/drm/panel/panel-kingdisplay-kd097d04.c

···
 	struct kingdisplay_panel *kingdisplay = mipi_dsi_get_drvdata(dsi);
 	int err;
 
-	err = drm_panel_unprepare(&kingdisplay->base);
-	if (err < 0)
-		dev_err(&dsi->dev, "failed to unprepare panel: %d\n", err);
-
-	err = drm_panel_disable(&kingdisplay->base);
-	if (err < 0)
-		dev_err(&dsi->dev, "failed to disable panel: %d\n", err);
-
 	err = mipi_dsi_detach(dsi);
 	if (err < 0)
 		dev_err(&dsi->dev, "failed to detach from DSI host: %d\n", err);
 
 	kingdisplay_panel_del(kingdisplay);
-}
-
-static void kingdisplay_panel_shutdown(struct mipi_dsi_device *dsi)
-{
-	struct kingdisplay_panel *kingdisplay = mipi_dsi_get_drvdata(dsi);
-
-	drm_panel_unprepare(&kingdisplay->base);
-	drm_panel_disable(&kingdisplay->base);
 }
 
 static struct mipi_dsi_driver kingdisplay_panel_driver = {
···
 	},
 	.probe = kingdisplay_panel_probe,
 	.remove = kingdisplay_panel_remove,
-	.shutdown = kingdisplay_panel_shutdown,
 };
 module_mipi_dsi_driver(kingdisplay_panel_driver);