[non-BE][allow-regression][split-non-BE] Resolve: "[Regression2553] Click in OMASA LTV, 2nd MASA Channel"

• Related issues: #2517
• Requested reviewers: @jander

Reason why this change is needed

• Click in OMASA LTV, 2nd MASA Channel.

Description of the change

• Normalize inputs of calc_residu_fx()
• Improve locally signal precision for LP analysis to preserve LSP accuracy in low-Q SCE path

Affected operating points

• Produced bitstream is non-BE.