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 <[e-mail]>
Signed-off-by: Neil Armstrong <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/meson/meson_drv.c

···
 	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)