dt-bindings: clock: Convert fixed-clock binding to json-schema

Binding for simple fixed-rate clock sources.

This binding uses the common clock binding[1].

[1] Documentation/devicetree/bindings/clock/clock-bindings.txt

Required properties:

- compatible : shall be "fixed-clock".

- #clock-cells : from common clock binding; shall be set to 0.

- clock-frequency : frequency of clock in Hz. Should be a single cell.

Optional properties:

- clock-accuracy : accuracy of clock in ppb (parts per billion).

		   Should be a single cell.

- clock-output-names : From common clock binding.

Example:

	clock {

		compatible = "fixed-clock";

		#clock-cells = <0>;

		clock-frequency = <1000000000>;

		clock-accuracy = <100>;

	};

# SPDX-License-Identifier: GPL-2.0

%YAML 1.2

---

$id: http://devicetree.org/schemas/clock/fixed-clock.yaml#

$schema: http://devicetree.org/meta-schemas/core.yaml#

title: Binding for simple fixed-rate clock sources

maintainers:

  - Michael Turquette <mturquette@baylibre.com>

  - Stephen Boyd <sboyd@kernel.org>

properties:

  compatible:

    const: fixed-clock

  "#clock-cells":

    const: 0

  clock-frequency: true

  clock-accuracy:

    description: accuracy of clock in ppb (parts per billion).

    $ref: /schemas/types.yaml#/definitions/uint32

  clock-output-names:

    maxItems: 1

required:

  - compatible

  - "#clock-cells"

  - clock-frequency

additionalProperties: false

examples:

  - |

    clock {

      compatible = "fixed-clock";

      #clock-cells = <0>;

      clock-frequency = <1000000000>;

      clock-accuracy = <100>;

    };

...