ASoC: dt-bindings: stm32: convert spdfirx to json-schema

Convert the STM32 SPDIFRX bindings to DT schema format using json-schema.

Signed-off-by: Olivier Moysan <olivier.moysan@st.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20200117170352.16040-1-olivier.moysan@st.com


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