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

Convert the fixed-clock binding to DT schema format using json-schema.

Cc: Michael Turquette <mturquette@baylibre.com>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: linux-clk@vger.kernel.org
Signed-off-by: Rob Herring <robh@kernel.org>
[sboyd@kernel.org: Drop full stop on title]
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

Documentation/devicetree/bindings/clock/fixed-clock.txt

-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>;
-	};

Documentation/devicetree/bindings/clock/fixed-clock.yaml

+# 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>;
+    };
+...