Align pre_proc_ivas() between FLP and BASOP

• Related issues: #2344
• Requested reviewers:

Reason why this change is needed

• The pre-processing functions are not always aligned between FLP and BASOP.

Description of the change

• The goal is to align FLP and BASOP codes for the pre-processing.

Affected operating points

• All is BE.

Closes #2344