dt-bindings: gpio: Convert cirrus,clps711x-mctrl-gpio to DT schema

Convert the cirrus,clps711x-mctrl-gpio binding to DT schema format.
Add the missing "gpio,syscon-dev" phandle property.

Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://lore.kernel.org/r/20250714202919.3012764-1-robh@kernel.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

Documentation/devicetree/bindings/gpio/cirrus,clps711x-mctrl-gpio.txt

@@ -1,17 +0,0 @@
-* ARM Cirrus Logic CLPS711X SYSFLG1 MCTRL GPIOs
-
-Required properties:
-- compatible: Should contain "cirrus,ep7209-mctrl-gpio".
-- gpio-controller: Marks the device node as a gpio controller.
-- #gpio-cells: Should be two. The first cell is the pin number and
-  the second cell is used to specify the gpio polarity:
-    0 = Active high,
-    1 = Active low.
-
-Example:
-	sysgpio: sysgpio {
-		compatible = "cirrus,ep7312-mctrl-gpio",
-			     "cirrus,ep7209-mctrl-gpio";
-		gpio-controller;
-		#gpio-cells = <2>;
-	};

Documentation/devicetree/bindings/gpio/cirrus,clps711x-mctrl-gpio.yaml

@@ -0,0 +1,49 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/gpio/cirrus,clps711x-mctrl-gpio.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: ARM Cirrus Logic CLPS711X SYSFLG1 MCTRL GPIOs
+
+maintainers:
+  - Alexander Shiyan <shc_work@mail.ru>
+
+properties:
+  compatible:
+    oneOf:
+      - items:
+          - const: cirrus,ep7312-mctrl-gpio
+          - const: cirrus,ep7209-mctrl-gpio
+      - const: cirrus,ep7209-mctrl-gpio
+
+  gpio-controller: true
+
+  '#gpio-cells':
+    const: 2
+
+  gpio,syscon-dev:
+    description:
+      Phandle and offset of device's specific registers within the syscon state
+      control registers
+    $ref: /schemas/types.yaml#/definitions/phandle-array
+    items:
+      - items:
+          - description: phandle to syscon
+          - description: register offset within state control registers
+
+required:
+  - compatible
+  - gpio-controller
+  - '#gpio-cells'
+
+additionalProperties: false
+
+examples:
+  - |
+    sysgpio: sysgpio {
+        compatible = "cirrus,ep7312-mctrl-gpio",
+                     "cirrus,ep7209-mctrl-gpio";
+        gpio-controller;
+        #gpio-cells = <2>;
+    };