tests: spurious failure fix for quota-anon-fd-nfs.t

Change-Id: I4f7ee68c514d8d322e25cf74167f288a8b6f8164
BUG: 1163543
Signed-off-by: Atin Mukherjee <amukherj@redhat.com>
Reviewed-on: http://review.gluster.org/9108
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Niels de Vos <ndevos@redhat.com>