ASoC: SOF: add snd_sof_device_shutdown() helper for shutdown

Add helper snd_sof_device_shutdown() to wrap the platform specific
.shutdown callbacks for SOF platforms.

Signed-off-by: Keyon Jie <yang.jie@linux.intel.com>
Reviewed-by: Bard Liao <bard.liao@intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Signed-off-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Link: https://lore.kernel.org/r/20210113152617.4048541-2-kai.vehmanen@linux.intel.com


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