ASoC: fsl_xcvr: Remove unused of_id variable

The of_id variable is not used, so just remove it.

Signed-off-by: Fabio Estevam <festevam@gmail.com>
Link: https://lore.kernel.org/r/20210118123815.1630882-3-festevam@gmail.com


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