Clarify licensing of the different pats of the toolkit

[furtiman]

I'd like to be clear on the licenses with which different parts of the toolkit are distributed.

I'm interested in both host tools (the python wheel of RKNN API), as well as on-device runtimes.

E.g., in rknn toolkit 2 repo they have this non-standard license:
https://github.com/airockchip/rknn-toolkit2/blob/master/LICENSE

But the header of the rknn linux runtime contains a non-permissive proprietary license:

rknn-toolkit2/rknpu2/runtime/Linux/librknn_api/include/rknn_api.h

Line 6 in a8dd54d

* of Rockchip Corporation. This is proprietary information owned by

The newer rkllm runtimes do not have it, and have a common license for the whole repo, no license in header
https://github.com/airockchip/rknn-llm/blob/main/rkllm-runtime/Linux/librkllm_api/include/rkllm.h

Please clarify and introduce a common license!
cc @airockchip