ASoC: dt-bindings: stm32: add missing port property

Add missing port property in STM32 SPDIFRX binding.
This will prevent potential warning:
Unevaluated properties are not allowed ('port' was unexpected)

Signed-off-by: Olivier Moysan <olivier.moysan@foss.st.com>
Link: https://patch.msgid.link/20241105135942.526624-1-olivier.moysan@foss.st.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: Olivier Moysan

Documentation/devicetree/bindings/sound/st,stm32-spdifrx.yaml

@@ -50,6 +50,10 @@ properties:
   resets:
     maxItems: 1
 
+  port:
+    $ref: audio-graph-port.yaml#
+    unevaluatedProperties: false
+
   access-controllers:
     minItems: 1
     maxItems: 2