Remove duplicates for decode_indexes function
# Basic info
<!--- Add commit SHA used to reproduce-->
# Bug description
There exist 2 overlapping functions decode_indexes_ivas_fx() and decode_indexes_fx(). Within these functions there are also several table addresses computations that need to be made with BASOP ops.
Also at least the related variables table_no_cv and table_no_cv_fx are duplicated.
# Ways to reproduce
Box folder: ...\\Box_EXTERNAL_IVAS_BASOP_VERIFICATION\\issues\\issue-xxxx
<!--Commandline or script-->
```bash
```
<!--- Below are labels that will be added but are not shown in description. This is a template to help fill them.
Add further information to the first row and remove and add labels as necessary.-->
issue