drm/rockchip: analogix_dp: Add a sanity check for rockchip_drm_psr_register()

The rockchip_drm_psr_register() can fail, so add a sanity check for that.
Signed-off-by: Jeffy Chen <jeffy.chen@rock-chips.com>
Signed-off-by: Thierry Escande <thierry.escande@collabora.com>
[moved psr_unregister reordering in unbind to separate patch]
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20180110162348.22765-4-thierry.escande@collabora.com

drivers/gpu/drm/rockchip/analogix_dp-rockchip.c

@@ -354,15 +354,22 @@ static int rockchip_dp_bind(struct device *dev, struct device *master,
 	dp->psr_state = ~EDP_VSC_PSR_STATE_ACTIVE;
 	INIT_WORK(&dp->psr_work, analogix_dp_psr_work);
 
-	rockchip_drm_psr_register(&dp->encoder, analogix_dp_psr_set);
+	ret = rockchip_drm_psr_register(&dp->encoder, analogix_dp_psr_set);
+	if (ret < 0)
+		goto err_cleanup_encoder;
 
 	dp->adp = analogix_dp_bind(dev, dp->drm_dev, &dp->plat_data);
 	if (IS_ERR(dp->adp)) {
-		dp->encoder.funcs->destroy(&dp->encoder);
-		return PTR_ERR(dp->adp);
+		ret = PTR_ERR(dp->adp);
+		goto err_unreg_psr;
 	}
 
 	return 0;
+err_unreg_psr:
+	rockchip_drm_psr_unregister(&dp->encoder);
+err_cleanup_encoder:
+	dp->encoder.funcs->destroy(&dp->encoder);
+	return ret;
 }
 
 static void rockchip_dp_unbind(struct device *dev, struct device *master,