ASoC: soc-dai: Add private data to snd_soc_dai

Add a private data pointer that can be used to store context along
with the DAI. This will be useful to allow the SDCA class library to
store data separately from the CODEC driver itself.

Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.dev>
Link: https://patch.msgid.link/20250707124155.2596744-5-ckeepax@opensource.cirrus.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: charleskeepax

include/sound/soc-dai.h

@@ -463,6 +463,9 @@ struct snd_soc_dai {
 
 	/* bit field */
 	unsigned int probed:1;
+
+	/* DAI private data */
+	void *priv;
 };
 
 static inline const struct snd_soc_pcm_stream *