ASoC: au1x: use asoc_substream_to_rtd()

Now we can use asoc_substream_to_rtd() macro,
let's use it.
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Link: https://lore.kernel.org/r/874kq30ysm.wl-kuninori.morimoto.gx@renesas.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/au1x/db1200.c

@@ -94,7 +94,7 @@ static struct snd_soc_card db1550_ac97_machine = {
 
 static int db1200_i2s_startup(struct snd_pcm_substream *substream)
 {
-	struct snd_soc_pcm_runtime *rtd = substream->private_data;
+	struct snd_soc_pcm_runtime *rtd = asoc_substream_to_rtd(substream);
 	struct snd_soc_dai *codec_dai = asoc_rtd_to_codec(rtd, 0);
 
 	/* WM8731 has its own 12MHz crystal */

sound/soc/au1x/dbdma2.c

@@ -278,7 +278,7 @@ static int au1xpsc_pcm_open(struct snd_soc_component *component,
 			    struct snd_pcm_substream *substream)
 {
 	struct au1xpsc_audio_dmadata *pcd = to_dmadata(substream, component);
-	struct snd_soc_pcm_runtime *rtd = substream->private_data;
+	struct snd_soc_pcm_runtime *rtd = asoc_substream_to_rtd(substream);
 	int stype = substream->stream, *dmaids;
 
 	dmaids = snd_soc_dai_get_dma_data(asoc_rtd_to_cpu(rtd, 0), substream);

sound/soc/au1x/dma.c

@@ -191,7 +191,7 @@ static int alchemy_pcm_open(struct snd_soc_component *component,
 			    struct snd_pcm_substream *substream)
 {
 	struct alchemy_pcm_ctx *ctx = ss_to_ctx(substream, component);
-	struct snd_soc_pcm_runtime *rtd = substream->private_data;
+	struct snd_soc_pcm_runtime *rtd = asoc_substream_to_rtd(substream);
 	int *dmaids, s = substream->stream;
 	char *name;