dt-bindings: npu: rockchip,rknn: Add bindings

Add the bindings for the Neural Processing Unit IP from Rockchip.

v2:
- Adapt to new node structure (one node per core, each with its own
  IOMMU)
- Several misc. fixes from Sebastian Reichel

v3:
- Split register block in its constituent subblocks, and only require
  the ones that the kernel would ever use (Nicolas Frattaroli)
- Group supplies (Rob Herring)
- Explain the way in which the top core is special (Rob Herring)

v4:
- Change required node name to npu@ (Rob Herring and Krzysztof Kozlowski)
- Remove unneeded items: (Krzysztof Kozlowski)
- Fix use of minItems/maxItems (Krzysztof Kozlowski)
- Add reg-names to list of required properties (Krzysztof Kozlowski)
- Fix example (Krzysztof Kozlowski)

v5:
- Rename file to rockchip,rk3588-rknn-core.yaml (Krzysztof Kozlowski)
- Streamline compatible property (Krzysztof Kozlowski)

v6:
- Remove mention to NVDLA, as the hardware is only incidentally related
  (Kever Yang)
- Mark pclk and npu clocks as required by all clocks (Rob Herring)

v7:
- Remove allOf section, not needed now that all nodes require 4 clocks
  (Heiko Stübner)

v8:
- Remove notion of top core (Robin Murphy)

Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Tomeu Vizoso <tomeu@tomeuvizoso.net>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Jeff Hugo <jeff.hugo@oss.qualcomm.com>
Link: https://lore.kernel.org/r/20250721-6-10-rocket-v9-6-77ebd484941e@tomeuvizoso.net