Optimized CSR stalls

Created by: silabs-oysteink

Conservatively stalling ID for any implicit CSR read while any implicit or explicit CSR write is in EX or WB (unchanged) Conservatively stalling EX for any implicit CSR read while any implicit or explicit CSR write is in WB Conservatively stalling EX for any explicit CSR rad while any implicit CSR write is in WB Precisely stalling EX for any explicit CSR read while an explicit CSR write to the same CSR is in WB.