ASoC: SOF: sof-client: Add API to get the maximum IPC payload size

Provide a way for the client drivers to query the maximum payload size of
an IPC message.
Currently clients do not have access to this information and they can only
use the SOF_IPC_MSG_MAX_SIZE defined value.

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>
Link: https://lore.kernel.org/r/20220506132647.18690-2-peter.ujfalusi@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>