ASoC: SOF: make ctx_store and ctx_restore as optional

Commit 657774ac ("ASoC: SOF: Make sof_suspend/resume IPC agnostic")
did not marked ctx_store and ctx_restore as Optional.

Fixes: 657774ac ("ASoC: SOF: Make sof_suspend/resume IPC agnostic")
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Reviewed-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20220610083549.16773-2-peter.ujfalusi@linux.intel.com


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