ASoC: dt-bindings: qcom,sm8250: Add Fairphone 4 sound card

Document the bindings for the sound card on Fairphone 4 which uses the
older non-audioreach audio architecture.

Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Luca Weiss <luca.weiss@fairphone.com>
Link: https://patch.msgid.link/20250723-fp4-usb-audio-offload-v3-2-6be84ed4fc39@fairphone.com


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