ASoC: SOF: topology: Modify the get_token op for string tokens

Modify the get_token op for string type tokens to pass the string as the
argument instead of a pointer to struct snd_soc_tplg_vendor_string_elem.

Signed-off-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Reviewed-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Reviewed-by: Péter Ujfalusi <peter.ujfalusi@linux.intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20220307181111.49392-9-ranjani.sridharan@linux.intel.com


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