ASoC: wm8750: convert to the json-schema

This helps validating DTS files.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20210512205926.780-1-zajec5@gmail.com


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