dt-bindings: arm: bcm: Convert Vulcan to YAML

Update Vulcan SoC family binding document for boards/SoCs to use YAML.
Verified with dt_binding_check and dtbs_check.
Acked-by: Scott Branden <scott.branden@broadcom.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>

Documentation/devicetree/bindings/arm/bcm/brcm,vulcan-soc.txt

-Broadcom Vulcan device tree bindings
-------------------------------------
-
-Boards with Broadcom Vulcan shall have the following root property:
-
-Broadcom Vulcan Evaluation Board:
-  compatible = "brcm,vulcan-eval", "brcm,vulcan-soc";
-
-Generic Vulcan board:
-  compatible = "brcm,vulcan-soc";

Documentation/devicetree/bindings/arm/bcm/brcm,vulcan-soc.yaml

+# SPDX-License-Identifier: GPL-2.0
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/arm/bcm/brcm,vulcan-soc.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Broadcom Vulcan device tree bindings
+
+maintainers:
+  - Robert Richter <rrichter@marvell.com>
+
+properties:
+  $nodename:
+    const: '/'
+  compatible:
+    items:
+      - enum:
+        - brcm,vulcan-eval
+        - cavium,thunderx2-cn9900
+      - const: brcm,vulcan-soc
+
+...