Resolve: basop issue 2611: "Wrong Q value comment in fucntion stereo_dft_sg_recovery_fx()"

• Related issues: #2611
• Requested reviewers: @multrus

Reason why this change is needed

• The comment corrected is misleading and it could confuse future refactoring and porting efforts.

Description of the change

• Corrected comment (Q13 --> Q31)

Affected operating points

• BE. No change in behavior is expected.