ASoC: dt-bindings: nau8821: Convert to dtschema

Convert the NAU8821 audio CODEC bindings to DT schema.

Signed-off-by: Seven Lee <wtli@nuvoton.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20230628085009.1130318-1-wtli@nuvoton.com


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