ASoC: adau1977: convert text binding to yaml format

This change converts the old device-tree binding for ADAU1977 from text
format to the new yaml format.

Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20201110084754.46756-1-alexandru.ardelean@analog.com


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