ASoC/mpc5200: add to_psc_dma_stream() helper

Move the resolving of the psc_dma_stream pointer to a helper function
to reduce duplicate code

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

sound/soc/fsl/mpc5200_dma.h

@@ -68,6 +68,15 @@ struct psc_dma {
 	} stats;
 };
 
+/* Utility for retrieving psc_dma_stream structure from a substream */
+inline struct psc_dma_stream *
+to_psc_dma_stream(struct snd_pcm_substream *substream, struct psc_dma *psc_dma)
+{
+	if (substream->pstr->stream == SNDRV_PCM_STREAM_CAPTURE)
+		return &psc_dma->capture;
+	return &psc_dma->playback;
+}
+
 int mpc5200_audio_dma_create(struct of_device *op);
 int mpc5200_audio_dma_destroy(struct of_device *op);