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

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

Cc: Tsahee Zidenberg <tsahee@annapurnalabs.com>
Cc: Antoine Tenart <antoine.tenart@free-electrons.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: devicetree@vger.kernel.org
Signed-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/arm/al,alpine.txt

-Annapurna Labs Alpine Platform Device Tree Bindings
----------------------------------------------------------------
-
-Boards in the Alpine family shall have the following properties:
-
-* Required root node properties:
-compatible: must contain "al,alpine"
-
-* Example:
-
-/ {
-	model = "Annapurna Labs Alpine Dev Board";
-	compatible = "al,alpine";
-
-	...
-}

Documentation/devicetree/bindings/arm/al,alpine.yaml

+# SPDX-License-Identifier: GPL-2.0
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/arm/al,alpine.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Annapurna Labs Alpine Platform Device Tree Bindings
+
+maintainers:
+  - Tsahee Zidenberg <tsahee@annapurnalabs.com>
+  - Antoine Tenart <antoine.tenart@bootlin.com>
+
+properties:
+  compatible:
+    items:
+      - const: al,alpine
+  model:
+    items:
+      - const: "Annapurna Labs Alpine Dev Board"
+
+...