ASoC: SOF: Intel: hda-codec: use GPL-2.0-only license

All the HDAudio codec handling is completely specific to Linux and
completely dependency on GPL2.0 code, specifically the snd_hdac_
library.

There was no intention to have a dual-license for this code, this was
an oversight that needs to be corrected. Update the SPDX and
EXPORT_SYMBOL information, no functionality change otherwise.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Rander Wang <rander.wang@intel.com>
Reviewed-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Reviewed-by: Péter Ujfalusi <peter.ujfalusi@linux.intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Link: https://lore.kernel.org/r/20221027193540.259520-21-pierre-louis.bossart@linux.intel.com


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