dt-bindings: power: syscon-poweroff: Convert bindings to json-schema

Convert the Syscon poweroff bindings to DT schema format using
json-schema.
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/power/reset/syscon-poweroff.txt

-Generic SYSCON mapped register poweroff driver
-
-This is a generic poweroff driver using syscon to map the poweroff register.
-The poweroff is generally performed with a write to the poweroff register
-defined by the register map pointed by syscon reference plus the offset
-with the value and mask defined in the poweroff node.
-
-Required properties:
-- compatible: should contain "syscon-poweroff"
-- regmap: this is phandle to the register map node
-- offset: offset in the register map for the poweroff register (in bytes)
-- value: the poweroff value written to the poweroff register (32 bit access)
-
-Optional properties:
-- mask: update only the register bits defined by the mask (32 bit)
-
-Legacy usage:
-If a node doesn't contain a value property but contains a mask property, the
-mask property is used as the value.
-
-Default will be little endian mode, 32 bit access only.
-
-Examples:
-
-	poweroff {
-	   compatible = "syscon-poweroff";
-	   regmap = <&regmapnode>;
-	   offset = <0x0>;
-	   mask = <0x7a>;
-	};

Documentation/devicetree/bindings/power/reset/syscon-poweroff.yaml

+# SPDX-License-Identifier: GPL-2.0
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/power/reset/syscon-poweroff.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Generic SYSCON mapped register poweroff driver
+
+maintainers:
+  - Sebastian Reichel <sre@kernel.org>
+
+description: |+
+  This is a generic poweroff driver using syscon to map the poweroff register.
+  The poweroff is generally performed with a write to the poweroff register
+  defined by the register map pointed by syscon reference plus the offset
+  with the value and mask defined in the poweroff node.
+  Default will be little endian mode, 32 bit access only.
+
+properties:
+  compatible:
+    const: syscon-poweroff
+
+  mask:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description: Update only the register bits defined by the mask (32 bit).
+
+  offset:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description: Offset in the register map for the poweroff register (in bytes).
+
+  regmap:
+    $ref: /schemas/types.yaml#/definitions/phandle
+    description: Phandle to the register map node.
+
+  value:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description: The poweroff value written to the poweroff register (32 bit access).
+
+required:
+  - compatible
+  - regmap
+  - offset
+
+allOf:
+  - if:
+      not:
+        required:
+          - mask
+    then:
+      required:
+        - value
+
+examples:
+  - |
+    poweroff {
+      compatible = "syscon-poweroff";
+      regmap = <&regmapnode>;
+      offset = <0x0>;
+      mask = <0x7a>;
+    };