dt-bindings: arm: Convert Altera board/soc bindings to json-schema

Convert Altera SoC bindings to DT schema format using json-schema.

Cc: Mark Rutland <mark.rutland@arm.com>
Acked-by: Dinh Nguyen <dinguyen@kernel.org>
Cc: devicetree@vger.kernel.org
Signed-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/arm/altera.txt

-Altera's SoCFPGA platform device tree bindings
----------------------------------------------
-
-Boards with Cyclone 5 SoC:
-Required root node properties:
-compatible = "altr,socfpga-cyclone5", "altr,socfpga";
-
-Boards with Arria 5 SoC:
-Required root node properties:
-compatible = "altr,socfpga-arria5", "altr,socfpga";
-
-Boards with Arria 10 SoC:
-Required root node properties:
-compatible = "altr,socfpga-arria10", "altr,socfpga";

Documentation/devicetree/bindings/arm/altera.yaml

+# SPDX-License-Identifier: GPL-2.0
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/arm/altera.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Altera's SoCFPGA platform device tree bindings
+
+maintainers:
+  - Dinh Nguyen <dinguyen@kernel.org>
+
+properties:
+  compatible:
+    items:
+      - enum:
+        - altr,socfpga-cyclone5
+        - altr,socfpga-arria5
+        - altr,socfpga-arria10
+      - const: altr,socfpga
+...