ASoC: simple-scu-card: tidyup "prefix" parsing

simple-scu-card.c is supporting "prefix" which is used to avoid
DAI naming conflict when CPU/Codec matching.
But, sound card might have multi sub-devices, and each codec might need
each prefix.

Now, ASoC is supporting snd_soc_of_parse_node_prefix(), let's support
it on audio-graph-scu-card, too. It is keeping existing DT style.

It can't support each codec's prefix if sound card had multi sub-devices
without this patch.
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/generic/simple-scu-card.c

@@ -157,10 +157,17 @@ static int asoc_simple_card_dai_link_of(struct device_node *np,
 		if (ret < 0)
 			return ret;
 
+		/* check "prefix" from top node */
 		snd_soc_of_parse_audio_prefix(card,
 					      &priv->codec_conf,
 					      dai_link->codecs->of_node,
 					      PREFIX "prefix");
+		/* check "prefix" from each node if top doesn't have */
+		if (!priv->codec_conf.of_node)
+			snd_soc_of_parse_node_prefix(np,
+						     &priv->codec_conf,
+						     dai_link->codecs->of_node,
+						     "prefix");
 	}
 
 	ret = asoc_simple_card_of_parse_tdm(np, &dai_props->dai);