Replace riscv_ prefix by cv32e40p_ prefix in all RTL module names and file names

Created by: Silabs-ArjanB

I believe we should rename the top level module and its file name to cv32e40p_core and cv32e40p_core.sv respectively. The same/similar remark holds for all RTL modules/files; they should all have their riscv_ prefix replaced by the cv32e40p_ prefix in both module name and file name.

This will require updates in manifest files, testbenches, etc.

The top level file/module renaming has already been done (https://github.com/openhwgroup/cv32e40p/pull/349) as it impacts the verification repos. The renaming of all other RTL files/modules is still open.