[Non-BE] Resolve "USAN errors in OMASA JBM decoding"

• Related issues: #975 (closed)
• Requested reviewers: @vasilache

Reason why this change is needed

Clang usan sanitizer test in pipeline found an error for OMASA at 13.2 kbps.

The root of the problem is a check for channel aware mode in feeding a packet into JBM for all cases and not only for decoding EVS.

Description of the change

Make sure the check for channel aware mode/partial copy is done only for EVS bit streams.

Affected operating points

• JBM decoding at bit rate 13.2 kbps
• Produced bitstream is BE compared to previous state (no encoder change)

Related to #975 (closed)