[Non-BE] Resolve "MC RS does not reallocate the necessary number of channels on the heap"

• Related issues: #839 (closed)
• Requested reviewers: @vaclav

Reason why this change is needed

MC RS does not check if the number of channels needed on the heap are needed to be reallocated.

Description of the change

Reallocate also in case of MC rate switching

Affected operating points

• RS
• Produced bitstream is BE compared to previous state (no encoder changes)

Related to #834 (closed)