ASoC: SOF: pcm: Extend the optionality of IPC ops to IPC as well

The IPC ops are optional, but they require that the ops struct is to be
allocated with all callbacks set to NULL.

Update the code to extend the optionality to:
sdev->ipc == NULL
sdev->ipc->ops == NULL
sdev->ipc->ops->[pcm] == NULL
sdev->ipc->ops->[pcm]->ops == NULL (treated optional currently)

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Reviewed-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Reviewed-by: Rander Wang <rander.wang@intel.com>
Link: https://lore.kernel.org/r/20221221102328.9635-5-peter.ujfalusi@linux.intel.com


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