kmssdpsdesext: Do not unset a GVAlue if it is not yet initialized
kmssdpsdesext: Do not unset a GVAlue if it is not yet initialized

Change-Id: I11792bfacb92e4cffeb918e1725af05d9c67b45f

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