dt-bindings: atmel,hlcdc: convert pwm bindings to json-schema

Convert device tree bindings for Atmel's HLCDC PWM controller to YAML
format.
Signed-off-by: Dharma Balasubiramani <dharma.b@microchip.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20240202001733.91455-3-dharma.b@microchip.comSigned-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

Documentation/devicetree/bindings/pwm/atmel,hlcdc-pwm.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/pwm/atmel,hlcdc-pwm.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Atmel's HLCDC's PWM controller
+
+maintainers:
+  - Nicolas Ferre <nicolas.ferre@microchip.com>
+  - Alexandre Belloni <alexandre.belloni@bootlin.com>
+  - Claudiu Beznea <claudiu.beznea@tuxon.dev>
+
+description:
+  The LCDC integrates a Pulse Width Modulation (PWM) Controller. This block
+  generates the LCD contrast control signal (LCD_PWM) that controls the
+  display's contrast by software. LCDC_PWM is an 8-bit PWM signal that can be
+  converted to an analog voltage with a simple passive filter. LCD display
+  panels have different backlight specifications in terms of minimum/maximum
+  values for PWM frequency. If the LCDC PWM frequency range does not match the
+  LCD display panel, it is possible to use the standalone PWM Controller to
+  drive the backlight.
+
+properties:
+  compatible:
+    const: atmel,hlcdc-pwm
+
+  "#pwm-cells":
+    const: 3
+
+required:
+  - compatible
+  - "#pwm-cells"
+
+additionalProperties: false

Documentation/devicetree/bindings/pwm/atmel-hlcdc-pwm.txt

-Device-Tree bindings for Atmel's HLCDC (High-end LCD Controller) PWM driver
-
-The Atmel HLCDC PWM is subdevice of the HLCDC MFD device.
-See ../mfd/atmel-hlcdc.txt for more details.
-
-Required properties:
- - compatible: value should be one of the following:
-   "atmel,hlcdc-pwm"
- - pinctr-names: the pin control state names. Should contain "default".
- - pinctrl-0: should contain the pinctrl states described by pinctrl
-   default.
- - #pwm-cells: should be set to 3. This PWM chip use the default 3 cells
-   bindings defined in pwm.yaml in this directory.
-
-Example:
-
-	hlcdc: hlcdc@f0030000 {
-		compatible = "atmel,sama5d3-hlcdc";
-		reg = <0xf0030000 0x2000>;
-		clocks = <&lcdc_clk>, <&lcdck>, <&clk32k>;
-		clock-names = "periph_clk","sys_clk", "slow_clk";
-
-		hlcdc_pwm: hlcdc-pwm {
-			compatible = "atmel,hlcdc-pwm";
-			pinctrl-names = "default";
-			pinctrl-0 = <&pinctrl_lcd_pwm>;
-			#pwm-cells = <3>;
-		};
-	};