dt-bindings: rng: add bindings for Xiphera XIP8001B hwrng

Document the device tree bindings of Xiphera's XIP8001B-trng IP.
Signed-off-by: Atte Tommiska <atte.tommiska@xiphera.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Documentation/devicetree/bindings/rng/xiphera,xip8001b-trng.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/rng/xiphera,xip8001b-trng.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Xiphera XIP8001B-trng bindings
+
+maintainers:
+  - Atte Tommiska <atte.tommiska@xiphera.com>
+
+description: |
+  Xiphera FPGA-based true random number generator intellectual property core.
+
+properties:
+  compatible:
+    const: xiphera,xip8001b-trng
+
+  reg:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    rng@43c00000 {
+        compatible = "xiphera,xip8001b-trng";
+        reg = <0x43c00000 0x10000>;
+    };