drm/meson: pm resume add return errno branch

pm_resump api did not handle drm_mode_config_helper_resume error.
This change add handle to return drm_mode_config_helper_resume`s
error number. This code logic is aligned with api pm_suspend.
After this change, the code maybe a bit readable.
Signed-off-by: Bernard Zhao <bernard@vivo.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200428131747.2099-1-bernard@vivo.com

drivers/gpu/drm/meson/meson_drv.c

@@ -412,9 +412,7 @@ static int __maybe_unused meson_drv_pm_resume(struct device *dev)
 	if (priv->afbcd.ops)
 		priv->afbcd.ops->init(priv);
 
-	drm_mode_config_helper_resume(priv->drm);
-
-	return 0;
+	return drm_mode_config_helper_resume(priv->drm);
 }
 
 static int compare_of(struct device *dev, void *data)