soc: mediatek: Missing platform_device_unregister() on error in mtk_mmsys_probe()

Add the missing platform_device_unregister() before return
from mtk_mmsys_probe() in the error handling case.

Fixes: 667c7692 ("soc / drm: mediatek: Fix mediatek-drm device probing")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Reviewed-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Link: https://lore.kernel.org/r/20200506141317.119537-1-weiyongjun1@huawei.comSigned-off-by: Matthias Brugger <matthias.bgg@gmail.com>

drivers/soc/mediatek/mtk-mmsys.c

@@ -311,8 +311,10 @@ static int mtk_mmsys_probe(struct platform_device *pdev)
 
 	drm = platform_device_register_data(&pdev->dev, "mediatek-drm",
 					    PLATFORM_DEVID_AUTO, NULL, 0);
-	if (IS_ERR(drm))
+	if (IS_ERR(drm)) {
+		platform_device_unregister(clks);
 		return PTR_ERR(drm);
+	}
 
 	return 0;
 }