[non-BE] Resolve "Bug in renderer flush in OMASA JBM bitrate switching"

• Related issues: #1199 (closed)
• Requested reviewers: @paulusj

Reason why this change is needed

• Bug in renderer flush in OMASA JBM bitrate switching.

Description of the change

• The number of ISM channels in renderer flush is corrected.

Affected operating points

• Not BE in OMASA JBM bitrate switching.