ASoC: SOF: Mark snd_sof_dsp_ops.ipc_pcm_params() callback optional

AMD is only implementing an empty function to pass the required test and
it is going to be deprecated in favor of the IPC agnostic
set_stream_data_offset() callback.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Rander Wang <rander.wang@intel.com>
Reviewed-by: Daniel Baluta <daniel.baluta@nxp.com>
Signed-off-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Link: https://lore.kernel.org/r/20220310042720.976809-6-ranjani.sridharan@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>