drm/mediatek: disable all the planes in atomic_disable

Under shadow register case, we do not disable all the plane before
disable all the hardwares. Fix it.

Fixes: 9dc84e98a3 ("drm/mediatek: add shadow register support")

Signed-off-by: Bibby Hsieh <bibby.hsieh@mediatek.com>
Signed-off-by: CK Hu <ck.hu@mediatek.com>

drivers/gpu/drm/mediatek/mtk_drm_crtc.c

@@ -540,6 +540,7 @@ static void mtk_drm_crtc_atomic_disable(struct drm_crtc *crtc,
 	}
 	mtk_crtc->pending_planes = true;
 
+	mtk_drm_crtc_hw_config(mtk_crtc);
 	/* Wait for planes to be disabled */
 	drm_crtc_wait_one_vblank(crtc);