dt-bindings: dma: apple,admac: Add t6020-admac compatible

After discussion with the devicetree maintainers we agreed to not extend
lists with the generic compatible "apple,admac" anymore [1]. Use
"apple,t8103-admac" as base compatible as it is the SoC the driver and
bindings were written for.

admac on Apple's M2 Pro/Max/Ultra SoCs is compatible with
"apple,t8103-admac" so add its per-SoC compatible with the former as
fallback used by the existing driver.

[1]: https://lore.kernel.org/asahi/12ab93b7-1fc2-4ce0-926e-c8141cfe81bf@kernel.org/

Reviewed-by: Neal Gompa <neal@gompa.dev>
Acked-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Janne Grunau <j@jannau.net>

Documentation/devicetree/bindings/dma/apple,admac.yaml

@@ -22,12 +22,17 @@ allOf:
 
 properties:
   compatible:
-    items:
-      - enum:
-          - apple,t6000-admac
-          - apple,t8103-admac
-          - apple,t8112-admac
-      - const: apple,admac
+    oneOf:
+      - items:
+          - const: apple,t6020-admac
+          - const: apple,t8103-admac
+      - items:
+          - enum:
+              # Do not add additional SoC to this list.
+              - apple,t6000-admac
+              - apple,t8103-admac
+              - apple,t8112-admac
+          - const: apple,admac
 
   reg:
     maxItems: 1