dt-bindings: clock: Convert cirrus,ep7209-clk to DT schema

Convert the Cirrus EP7xxx (aka CLPS711x) binding to DT schema format.
It's a straight forward conversion.

Signed-off-by: Rob Herring (Arm) <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Stephen Boyd <[e-mail]>

Documentation/devicetree/bindings/clock/cirrus,ep7209-clk.yaml

···
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/clock/cirrus,ep7209-clk.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Cirrus Logic CLPS711X Clock Controller
+
+maintainers:
+  - Alexander Shiyan <[e-mail]>
+
+description:
+  See include/dt-bindings/clock/clps711x-clock.h for the full list of CLPS711X
+  clock IDs.
+
+properties:
+  compatible:
+    items:
+      - const: cirrus,ep7312-clk
+      - const: cirrus,ep7209-clk
+
+  reg:
+    maxItems: 1
+
+  startup-frequency:
+    description: Factory set CPU startup frequency in HZ.
+    $ref: /schemas/types.yaml#/definitions/uint32
+
+  "#clock-cells":
+    const: 1
+
+required:
+  - compatible
+  - reg
+  - startup-frequency
+  - "#clock-cells"
+
+additionalProperties: false
+
+examples:
+  - |
+    clock-controller@80000000 {
+        compatible = "cirrus,ep7312-clk", "cirrus,ep7209-clk";
+        reg = <0x80000000 0xc000>;
+        #clock-cells = <1>;
+        startup-frequency = <73728000>;
+    };

Documentation/devicetree/bindings/clock/clps711x-clock.txt

···
-* Clock bindings for the Cirrus Logic CLPS711X CPUs
-
-Required properties:
-- compatible       : Shall contain "cirrus,ep7209-clk".
-- reg              : Address of the internal register set.
-- startup-frequency: Factory set CPU startup frequency in HZ.
-- #clock-cells     : Should be <1>.
-
-The clock consumer should specify the desired clock by having the clock
-ID in its "clocks" phandle cell. See include/dt-bindings/clock/clps711x-clock.h
-for the full list of CLPS711X clock IDs.
-
-Example:
-	clks: clks@80000000 {
-		#clock-cells = <1>;
-		compatible = "cirrus,ep7312-clk", "cirrus,ep7209-clk";
-		reg = <0x80000000 0xc000>;
-		startup-frequency = <73728000>;
-	};