dt-bindings: sound: convert rockchip i2s bindings to yaml

Current dts files with 'i2s' nodes are manually verified.
In order to automate this process rockchip-i2s.txt
has to be converted to yaml.

Signed-off-by: Johan Jonker <jbx6244@gmail.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20200324094149.6904-1-jbx6244@gmail.com


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