drm/mediatek: Convert drm_atomic_helper_suspend/resume()

convert drm_atomic_helper_suspend/resume() to use
drm_mode_config_helper_suspend/resume().
Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
Signed-off-by: Ajit Negi <ajitn.linux@gmail.com>
Signed-off-by: CK Hu <ck.hu@mediatek.com>

drivers/gpu/drm/mediatek/mtk_drm_drv.c

@@ -580,29 +580,24 @@ static int mtk_drm_sys_suspend(struct device *dev)
 {
 	struct mtk_drm_private *private = dev_get_drvdata(dev);
 	struct drm_device *drm = private->drm;
+	int ret;
 
-	drm_kms_helper_poll_disable(drm);
-
-	private->suspend_state = drm_atomic_helper_suspend(drm);
-	if (IS_ERR(private->suspend_state)) {
-		drm_kms_helper_poll_enable(drm);
-		return PTR_ERR(private->suspend_state);
-	}
-
+	ret = drm_mode_config_helper_suspend(drm);
 	DRM_DEBUG_DRIVER("mtk_drm_sys_suspend\n");
-	return 0;
+
+	return ret;
 }
 
 static int mtk_drm_sys_resume(struct device *dev)
 {
 	struct mtk_drm_private *private = dev_get_drvdata(dev);
 	struct drm_device *drm = private->drm;
+	int ret;
 
-	drm_atomic_helper_resume(drm, private->suspend_state);
-	drm_kms_helper_poll_enable(drm);
-
+	ret = drm_mode_config_helper_resume(drm);
 	DRM_DEBUG_DRIVER("mtk_drm_sys_resume\n");
-	return 0;
+
+	return ret;
 }
 #endif