sdpagent: remove unnecessary private field
sdpagent: remove unnecessary private field

Change-Id: Ib3747a3fab3dc09c49064e44e912cee13ee187e8

ESTOS/kms-core,ESTOS/kms-core,Kurento/kms-core,Kurento/kms-core,Kurento/kms-core,ESTOS/kms-core,Kurento/kms-core,ESTOS/kms-core