ASoC: remove rtd->platform checck

Now, we are ready to replace rtd->platform to rtdcom list.
From this patch, rtd->platform check is no longer needed.
It will be replaced into rtdcom.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/soc-core.c

@@ -1162,11 +1162,6 @@ static int soc_bind_dai_link(struct snd_soc_card *card,
 
 		rtd->platform = platform;
 	}
-	if (!rtd->platform) {
-		dev_err(card->dev, "ASoC: platform %s not registered\n",
-			dai_link->platform_name);
-		goto _err_defer;
-	}
 
 	soc_add_pcm_runtime(card, rtd);
 	return 0;