ASoC: sgtl5000: Convert to json-schema

Convert the Freescale SGTL5000 device tree bindings from free-form text
format to json-schema.

Signed-off-by: Thierry Reding <treding@nvidia.com>
Link: https://lore.kernel.org/r/20200608174658.1315325-1-thierry.reding@gmail.com


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