dt-bindings: riscv: add starfive jh7100 bindings

Add DT binding documentation for the StarFive JH7100 Soc [1] and the
BeagleV Starlight JH7100 board [2].

[1] https://github.com/starfive-tech/beaglev_doc
[2] https://github.com/beagleboard/beaglev-starlightSigned-off-by: Drew Fustini <drew@beagleboard.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

Documentation/devicetree/bindings/riscv/starfive.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/riscv/starfive.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: StarFive SoC-based boards
+
+maintainers:
+  - Michael Zhu <michael.zhu@starfivetech.com>
+  - Drew Fustini <drew@beagleboard.org>
+
+description:
+  StarFive SoC-based boards
+
+properties:
+  $nodename:
+    const: '/'
+  compatible:
+    oneOf:
+      - items:
+          - const: beagle,beaglev-starlight-jh7100-r0
+          - const: starfive,jh7100
+
+additionalProperties: true
+
+...