Add generated control registers

[SamuelRiedel]

Replace our manually managed control registers with automatically generated ones using reggen. This will make it easier to modify and add new control registers.

Changelog

Changed

• Use automatically generated control registers

Checklist

• Automated tests pass
• Changelog updated
• Code style guideline is observed

[mbertuletti]

Is the tool invoked every time we compile the RTL for simulation? If not, does it make sense to add a helper target in the hardware/Makefile similar to the one we use to generate the bootroom?

[SamuelRiedel]

Is the tool invoked every time we compile the RTL for simulation? If not, does it make sense to add a helper target in the hardware/Makefile similar to the one we use to generate the bootroom?

I added a target that checks whether the HJSON was modified and that automatically updates the control register files in that case. It can also be used as the convenience target in the hardware/Makefile directly.