Remove unnecessary ariane_soc_pkg dependency

Created by: LucaZulberti

With my work, I had the necessity to remove the dependency of ariane_soc package from the CVA6 core. It was straightforward because *_slv_t types are needed only in ariane_testharness.

I'm not familiar with your build system (Bender, etc..) and I'm not sure this is the best solution to be maintained. If you are interested in isolating better the code of CVA6 from the SoC where it is instantiated, this patch aims to obtain this result.

Draft until interested and improved.