Fix HDL licenses and make reuse happy

reuse detects that many files in the hdl directory are unlicensed. Please, set the proper licence and then remove the allow_failure: true form the reuse CI job

You can do it using quickly https://reuse.software/

You can install it using pip

pipx install reuse

Then add header information with

reuse addheader -c CERN (home.cern) -y 2022 -l <LICENSE-NAME> <FILES>

and to check

reuse lint

Double-check the result