dt-bindings: rng: ti,keystone-rng: convert TI Keystone RNG to dtschema

Convert the TI Keystone RNG bindings to DT schema.
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20211227183251.132525-4-krzysztof.kozlowski@canonical.com

Documentation/devicetree/bindings/rng/ks-sa-rng.txt

-Keystone SoC Hardware Random Number Generator(HWRNG) Module
-
-On Keystone SoCs HWRNG module is a submodule of the Security Accelerator.
-
-- compatible: should be "ti,keystone-rng"
-- ti,syscon-sa-cfg: phandle to syscon node of the SA configuration registers.
-		    This registers are shared between hwrng and crypto drivers.
-- clocks: phandle to the reference clocks for the subsystem
-- clock-names: functional clock name. Should be set to "fck"
-- reg: HWRNG module register space
-
-Example:
-/* K2HK */
-
-rng@24000 {
-	compatible = "ti,keystone-rng";
-	ti,syscon-sa-cfg = <&sa_config>;
-	clocks = <&clksa>;
-	clock-names = "fck";
-	reg = <0x24000 0x1000>;
-};

Documentation/devicetree/bindings/rng/ti,keystone-rng.yaml

+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/rng/ti,keystone-rng.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Keystone SoC Hardware Random Number Generator
+
+maintainers:
+  - Nishanth Menon <nm@ti.com>
+  - Santosh Shilimkar <ssantosh@kernel.org>
+
+properties:
+  compatible:
+    const: ti,keystone-rng
+
+  clocks:
+    maxItems: 1
+
+  clock-names:
+    items:
+      - const: fck
+
+  reg:
+    maxItems: 1
+
+  ti,syscon-sa-cfg:
+    $ref: "/schemas/types.yaml#/definitions/phandle"
+    description: |
+      Phandle to syscon node of the SA configuration registers.  These
+      registers are shared between HWRNG and crypto drivers.
+
+required:
+  - compatible
+  - clocks
+  - clock-names
+  - reg
+  - ti,syscon-sa-cfg
+
+additionalProperties: false
+
+examples:
+  - |
+    rng@24000 {
+        compatible = "ti,keystone-rng";
+        ti,syscon-sa-cfg = <&sa_config>;
+        clocks = <&clksa>;
+        clock-names = "fck";
+        reg = <0x24000 0x1000>;
+    };