ASoC: SOF: Intel: hda-mlink: add helper to get sublink LSDIID register

We need to retrieve the current value to deal with the HDAudio
WAKEEN/WAKESTS setup.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@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/20230807210959.506849-18-pierre-louis.bossart@linux.intel.com


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