ASoC: dt-bindings: qcom,wcd934x: Describe slim-ifc-dev

The "slim-ifc-dev" property should not be just "true", because it allows
any type.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20230206180805.6621-2-krzysztof.kozlowski@linaro.org


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