kmsaudiomixerbin: Remove unused variables
kmsaudiomixerbin: Remove unused variables

Change-Id: I0af0fdfe465b7214b3b5243b14fac07d16aa91c9

ESTOS/kms-core,Kurento/kms-core,TribeMedia/kms-core,shelsonjava/kms-core,Kurento/kms-core,ESTOS/kms-core,shelsonjava/kms-core,KurentoLegacy/gst-kurento-plugins,KurentoLegacy/gst-kurento-plugins,KurentoLegacy/gst-kurento-plugins,shelsonjava/kms-core,TribeMedia/kms-core,ESTOS/kms-core,ESTOS/kms-core,Kurento/kms-core,TribeMedia/kms-core,shelsonjava/kms-core,Kurento/kms-core,TribeMedia/kms-core,KurentoLegacy/gst-kurento-plugins