[Non-BE] Resolve "JBM Crend early reflections are wrong"

• Related issues: #827 (closed)
• Requested reviewers: one of @ragot, @lefort, @emerit, @genovesea

Reason why this change is needed

The CREND processing in the JBM path is not correctly processing the early reflections, it is both accessing the wrong buffer and not handling the subframes correctly

Description of the change

Fix buffer access and subframe handling for CREND early reflections in the JBM path

Affected operating points

• JBM decoding where CREND with early reflections is used
• Produced bitstream is BE compared to previous state (no encoder changes).

Related to #827 (closed)