ASoC: dt-bindings: atmel,at91-ssc: add microchip,sam9x7-ssc

Add microchip,sam9x7-ssc to DT bindings documentation.

Signed-off-by: Varshini Rajendran <[e-mail]>
Acked-by: Rob Herring (Arm) <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Mark Brown <[e-mail]>

Documentation/devicetree/bindings/sound/atmel,at91-ssc.yaml

···
 
 properties:
   compatible:
-    enum:
-      - atmel,at91rm9200-ssc
-      - atmel,at91sam9g45-ssc
+    oneOf:
+      - enum:
+          - atmel,at91rm9200-ssc
+          - atmel,at91sam9g45-ssc
+      - items:
+          - enum:
+              - microchip,sam9x7-ssc
+          - const: atmel,at91sam9g45-ssc
 
   reg:
     maxItems: 1