drm/exynos: hdmi: add null check for hdmiphy_port

The hdmiphy can be apb and hdmiphy_port can be null. So before
accessing hdmiphy_port, it should be checked.
Signed-off-by: Seung-Woo Kim <sw0312.kim@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>

drivers/gpu/drm/exynos/exynos_hdmi.c

@@ -2521,6 +2521,7 @@ static int hdmi_remove(struct platform_device *pdev)
 	if (hdata->res.reg_hdmi_en)
 		regulator_disable(hdata->res.reg_hdmi_en);
 
+	if (hdata->hdmiphy_port)
 		put_device(&hdata->hdmiphy_port->dev);
 	put_device(&hdata->ddc_adpt->dev);