ASoC: dt-bindings: wcd938x: Add mic bias supply property

Add vdd mic bias supply, which is required to provide bias
for wcd938x codec.
Signed-off-by: Srinivasa Rao Mandadapu <quic_srivasam@quicinc.com>
Co-developed-by: Venkata Prasad Potturu <quic_potturu@quicinc.com>
Signed-off-by: Venkata Prasad Potturu <quic_potturu@quicinc.com>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/1647852981-27895-3-git-send-email-quic_srivasam@quicinc.comSigned-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/sound/qcom,wcd938x.yaml

@@ -36,6 +36,9 @@ properties:
   vdd-io-supply:
     description: A reference to the 1.8V I/O supply
 
+  vdd-mic-bias-supply:
+    description: A reference to the 3.8V mic bias supply
+
   qcom,tx-device:
     $ref: /schemas/types.yaml#/definitions/phandle-array
     description: A reference to Soundwire tx device phandle