Remove bbgain variable
Remove bbgain variable

Summary:
gain: Remove bbgain variable
Closes T782

Test Plan: Matlab test, unit test

Reviewers: tobias

Reviewed By: tobias

Maniphest Tasks: T782

Differential Revision: https://dev.openmha.org/D218

HoerTech-gGmbH/openMHA,HoerTech-gGmbH/openMHA,HoerTech-gGmbH/openMHA,HoerTech-gGmbH/openMHA,HoerTech-gGmbH/openMHA,HoerTech-gGmbH/openMHA,HoerTech-gGmbH/openMHA,HoerTech-gGmbH/openMHA