ASoC: dt-bindings: google,sc7280-herobrine: Add platform property

Add platform property in sc7280 machine driver bindings for including
platform subnode in dai-links.
This is required for binding the frontend dai driver to do dynamic pcm
routing in ADSP based platforms.

Signed-off-by: Srinivasa Rao Mandadapu <quic_srivasam@quicinc.com>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/1674468802-14834-3-git-send-email-quic_srivasam@quicinc.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/sound/google,sc7280-herobrine.yaml

@@ -75,6 +75,18 @@ patternProperties:
 
         additionalProperties: false
 
+      platform:
+        description: Holds subnode which includes the phandle of q6apm platform device.
+        type: object
+        properties:
+          sound-dai:
+            maxItems: 1
+
+        required:
+          - sound-dai
+
+        additionalProperties: false
+
     required:
       - link-name
       - cpu