5. core: Fix variable names in VdcReturnValueBase

Fix variable names and the the correspoding set and get
method names in VdcReturnValueBase and
VdcActionParametersBase

http://www.ovirt.org/Features/AsyncTaskManagerChanges_3.3
Change-Id: Iebfbd19f8eeef4a9a0d30eadaacb1d833cae0ec7
Signed-off-by: Ravi Nori <rnori@redhat.com>