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

Update the Broadocom Cygnus SoC 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,cygnus.txt

-Broadcom Cygnus device tree bindings
-------------------------------------
-
-
-Boards with Cygnus SoCs shall have the following properties:
-
-Required root node property:
-
-BCM11300
-compatible = "brcm,bcm11300", "brcm,cygnus";
-
-BCM11320
-compatible = "brcm,bcm11320", "brcm,cygnus";
-
-BCM11350
-compatible = "brcm,bcm11350", "brcm,cygnus";
-
-BCM11360
-compatible = "brcm,bcm11360", "brcm,cygnus";
-
-BCM58300
-compatible = "brcm,bcm58300", "brcm,cygnus";
-
-BCM58302
-compatible = "brcm,bcm58302", "brcm,cygnus";
-
-BCM58303
-compatible = "brcm,bcm58303", "brcm,cygnus";
-
-BCM58305
-compatible = "brcm,bcm58305", "brcm,cygnus";

Documentation/devicetree/bindings/arm/bcm/brcm,cygnus.yaml

+# SPDX-License-Identifier: GPL-2.0
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/arm/bcm/brcm,cygnus.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Broadcom Cygnus device tree bindings
+
+maintainers:
+   - Ray Jui <rjui@broadcom.com>
+   - Scott Branden <sbranden@broadcom.com>
+
+properties:
+  $nodename:
+    const: '/'
+  compatible:
+    items:
+      - enum:
+        - brcm,bcm11300
+        - brcm,bcm11320
+        - brcm,bcm11350
+        - brcm,bcm11360
+        - brcm,bcm58300
+        - brcm,bcm58302
+        - brcm,bcm58303
+        - brcm,bcm58305
+      - const: brcm,cygnus
+
+...