dt-bindings: i2c: Convert apm,xgene-slimpro-i2c to DT schema

Convert APM X-Gene slimpro-i2c binding to DT schema format. It's a
straight-forward conversion.

Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>

Author: robherring

Documentation/devicetree/bindings/i2c/apm,xgene-slimpro-i2c.yaml

@@ -0,0 +1,36 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/i2c/apm,xgene-slimpro-i2c.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: APM X-Gene SLIMpro Mailbox I2C
+
+maintainers:
+  - Khuong Dinh <khuong@os.amperecomputing.com>
+
+description:
+  An I2C controller accessed over the "SLIMpro" mailbox.
+
+allOf:
+  - $ref: /schemas/i2c/i2c-controller.yaml#
+
+properties:
+  compatible:
+    const: apm,xgene-slimpro-i2c
+
+  mboxes:
+    maxItems: 1
+
+required:
+  - compatible
+  - mboxes
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    i2c {
+        compatible = "apm,xgene-slimpro-i2c";
+        mboxes = <&mailbox 0>;
+    };