ASoC: dt-bindings: qcom,wcd934x: Allow usage as IFD device

ASoC: dt-bindings: qcom,wcd934x: Allow usage as IFD device

The WCD9340 audio codec appears on Slimbus twice: as IFD device without
properties and the actual audio-codec referencing the former via
wcd9340_ifd.  Allow in the binding both versions to fix several warnings
like:

  sdm850-samsung-w737.dtb: ifd@0,0: 'reset-gpios' is a required property
  sdm850-samsung-w737.dtb: ifd@0,0: 'slim-ifc-dev' is a required property
  sdm850-samsung-w737.dtb: ifd@0,0: 'interrupt-controller' is a required property

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20230206180805.6621-3-krzysztof.kozlowski@linaro.org
Signed-off-by: Mark Brown <broonie@kernel.org>