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.com


Signed-off-by: Mark Brown <broonie@kernel.org>