ASoC: arm: Use snd_soc_substream_to_rtd() for accessing private_data

Do not open-code snd_soc_substream_to_rtd().

Signed-off-by: Krzysztof Kozlowski <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Mark Brown <[e-mail]>

sound/arm/pxa2xx-pcm-lib.c

···
 			 struct snd_pcm_hw_params *params)
 {
 	struct dma_chan *chan = snd_dmaengine_pcm_get_chan(substream);
-	struct snd_soc_pcm_runtime *rtd = substream->private_data;
+	struct snd_soc_pcm_runtime *rtd = snd_soc_substream_to_rtd(substream);
 	struct snd_dmaengine_dai_dma_data *dma_params;
 	struct dma_slave_config config;
 	int ret;
···
 
 int pxa2xx_pcm_open(struct snd_pcm_substream *substream)
 {
-	struct snd_soc_pcm_runtime *rtd = substream->private_data;
+	struct snd_soc_pcm_runtime *rtd = snd_soc_substream_to_rtd(substream);
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	struct snd_dmaengine_dai_dma_data *dma_params;
 	int ret;