kmsaudiomixer: Remove extra object reference to avoid a memory leak
kmsaudiomixer: Remove extra object reference to avoid a memory leak

Change-Id: I635018bbc653ff8b895136e02a36a22d863c65fb

TribeMedia/kms-core,Kurento/kms-core,Kurento/kms-core,ESTOS/kms-core,shelsonjava/kms-core,ESTOS/kms-core,Kurento/kms-core,shelsonjava/kms-core,TribeMedia/kms-core,TribeMedia/kms-core,ESTOS/kms-core,TribeMedia/kms-core,Kurento/kms-core,ESTOS/kms-core,shelsonjava/kms-core,shelsonjava/kms-core