dt-bindings: pxa-pwm: Convert to YAML

Convert the PXA PWM binding file from TXT to YAML.

The original binding does not mention any clocks, but the PWM controller
will not probe without a clock.
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Duje Mihanović <duje.mihanovic@skole.hr>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20240107-pxa-pwm-yaml-v3-1-92ac90911c3f@skole.hrSigned-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

Documentation/devicetree/bindings/pwm/marvell,pxa-pwm.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/pwm/marvell,pxa-pwm.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Marvell PXA PWM
+
+maintainers:
+  - Duje Mihanović <duje.mihanovic@skole.hr>
+
+allOf:
+  - $ref: pwm.yaml#
+
+properties:
+  compatible:
+    enum:
+      - marvell,pxa250-pwm
+      - marvell,pxa270-pwm
+      - marvell,pxa168-pwm
+      - marvell,pxa910-pwm
+
+  reg:
+    # Length should be 0x10
+    maxItems: 1
+
+  "#pwm-cells":
+    # Used for specifying the period length in nanoseconds
+    const: 1
+
+  clocks:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+  - "#pwm-cells"
+  - clocks
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/clock/pxa-clock.h>
+
+    pwm0: pwm@40b00000 {
+      compatible = "marvell,pxa250-pwm";
+      reg = <0x40b00000 0x10>;
+      #pwm-cells = <1>;
+      clocks = <&clks CLK_PWM0>;
+    };

Documentation/devicetree/bindings/pwm/pxa-pwm.txt

-Marvell PWM controller
-
-Required properties:
-- compatible: should be one or more of:
-  - "marvell,pxa250-pwm"
-  - "marvell,pxa270-pwm"
-  - "marvell,pxa168-pwm"
-  - "marvell,pxa910-pwm"
-- reg: Physical base address and length of the registers used by the PWM channel
-  Note that one device instance must be created for each PWM that is used, so the
-  length covers only the register window for one PWM output, not that of the
-  entire PWM controller.  Currently length is 0x10 for all supported devices.
-- #pwm-cells: Should be 1.  This cell is used to specify the period in
-  nanoseconds.
-
-Example PWM device node:
-
-pwm0: pwm@40b00000 {
-	compatible = "marvell,pxa250-pwm";
-	reg = <0x40b00000 0x10>;
-	#pwm-cells = <1>;
-};
-
-Example PWM client node:
-
-backlight {
-	compatible = "pwm-backlight";
-	pwms = <&pwm0 5000000>;
-	...
-}