glusterd: pass the right argument for perf subgraph

Change-Id: Ic292dcd8e477066c1079f0f1e170f5153459b029
Signed-off-by: Krishnan Parthasarathi <kparthas@redhat.com>
Reviewed-on: http://review.gluster.org/7514
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Anand Avati <avati@redhat.com>