Change of license to BSD-2-Clause

[dehanj]

We are changing to the more permissive BSD-2-clause license for all Verilog and source code.

The main reason to change the license is to allow more people and organizations to use our design and our code.

• Change the license of all files (at least with GPL) to BSD-2-Clause
•  Change project license to BSD-2-Clause
• Follow the REUSE Specification and run a REUSE check in CI