ASoC: dt-bindings: document wcd937x Audio Codec

Document the Qualcomm WCD9370/WCD9375 Audio Codec and the
Soundwire devices than can be found on Qualcomm QCM6490 based platforms.

The Qualcomm WCD9370/WCD9375 Audio Codec communicates
with the host SoC over 2 Soundwire links to provide:
- 3 TX ADC paths with 4 differential AMIC inputs
- 6 DMIC inputs that are shared with AMIC input
- 4 Microphone BIAS
- RX paths with 4 PAs – HPHL/R, EAR and AUX
- Stereo Headphone output
- MBHC engine for Headset Detection

Signed-off-by: Prasad Kumpatla <quic_pkumpatl@quicinc.com>
Co-developed-by: Mohammad Rafi Shaik <quic_mohs@quicinc.com>
Signed-off-by: Mohammad Rafi Shaik <quic_mohs@quicinc.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20240524035535.3119208-2-quic_mohs@quicinc.com
Signed-off-by: Mark Brown <broonie@kernel.org>