ASoC: SOF: Introduce opaque storage of private data for firmware tracing

Firmware tracing implementations can allocate and store their privately
used data behind the fw_trace_pdata pointer instead of adding more
members to struct snd_sof_dev.
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
Reviewed-by: Paul Olaru <paul.olaru@oss.nxp.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Link: https://lore.kernel.org/r/20220516104711.26115-8-peter.ujfalusi@linux.intel.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/sof/sof-priv.h

@@ -549,6 +549,7 @@ struct snd_sof_dev {
 
 	/* firmwre tracing */
 	bool fw_trace_is_supported; /* set with Kconfig or module parameter */
+	void *fw_trace_data; /* private data used by firmware tracing implementation */
 
 	/* DMA for Trace */
 	struct snd_dma_buffer dmatb;