Partial fix for issue #766 (!833) · Merge requests · OpenHW Group / backup-20241120 / cv32e40x

Created by: silabs-oysteink

Changes CSR implementation to be identical to the unhardened version on cv32e40s
Introduces MASK and RESET_VAL for all CSRs
Use a function to compute next value for all next-value assignments

This should align X and S better, and allow for unimplemented bits in CSRs to be either 0 or 1.

Once this PR is approved, similar changes will be done for the remaining CSRs.

SEC clean.

Partial fix for issue #766