dt-bindings: rng: st,rng: convert ST RNG to dtschema

Convert the ST 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/20211227183251.132525-7-krzysztof.kozlowski@canonical.com

Documentation/devicetree/bindings/rng/st,rng.yaml

@@ -0,0 +1,35 @@
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/rng/st,rng.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: STMicroelectronics Hardware Random Number Generator
+
+maintainers:
+  - Patrice Chotard <patrice.chotard@foss.st.com>
+
+properties:
+  compatible:
+    const: st,rng
+
+  clocks:
+    maxItems: 1
+
+  reg:
+    maxItems: 1
+
+required:
+  - compatible
+  - clocks
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    rng@fee80000 {
+        compatible = "st,rng";
+        reg = <0xfee80000 0x1000>;
+        clocks = <&clk_sysin>;
+    };