Resolve "[CLANG18] MSAN: use-of-uninitialized-value in lib_dec/hq_hr_dec_fx.c:632:5"

• Related issues: #2391 (closed)
• Requested reviewers: @norvell

Reason why this change is needed

The variable hq_generic_offset might remain uninitialized in certain cases.

Description of the change

Initialize hq_generic_offset in hq_hr_dec_fx(), replicate what is done in ivas_hq_hr_dec_fx()

Affected operating points

All operating points remain BE

Closes #2391 (closed)