dt-bindings: arm: add AMD Pensando boards

Document the compatible for AMD Pensando Elba SoC boards.

Signed-off-by: Brad Larson <[e-mail]>
Reviewed-by: Rob Herring <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Arnd Bergmann <[e-mail]>

Documentation/devicetree/bindings/arm/amd,pensando.yaml

···
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/arm/amd,pensando.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: AMD Pensando SoC Platforms
+
+maintainers:
+  - Brad Larson <[e-mail]>
+
+properties:
+  $nodename:
+    const: "/"
+  compatible:
+    oneOf:
+
+      - description: Boards with Pensando Elba SoC
+        items:
+          - enum:
+              - amd,pensando-elba-ortano
+          - const: amd,pensando-elba
+
+additionalProperties: true
+
+...