[non-BE] Resolve "Bug in FD BWE memory updates at low bitrates"

• Related issues: #2408 (closed)
• Requested reviewers:

Reason why this change is needed

• The FD BWE memory updates in the function wb_pre_proc_ivas_fx() are missing due to a bug in the following condition.

Description of the change

• Correction of a bug in the FD BWE memory updates in the function wb_pre_proc_ivas_fx().

Affected operating points

• Not BE at the lowest bitrates of ISM, subjective differences are negligible.

Closes #2408 (closed)