Reduce gate count of csr_regfile.sv

[JeanRochCoulon]

Task Description

read_access_exception is by default set to zero in RTL. When CSR is unimplemented, it is set to one. This is costy in term og gate count.

Required Changes

Set read_access_exception set to one by default and set it to zero when CSR is implemented..

Current Status

not started

Risks

To prevent from functionality regression, CSR tests should be used.

Prerequisites

Need to have a CSR test.

KPI (KEY Performance Indicators)

Gate count

Description of Done

The gate count is lower and no functional regression

Associated PRs

No response