nufa: allow subvols with fanout > 1

Previously, nufa wouldn't work on volume topologies such as
distribute-replicate or distribute-stripe.

Change-Id: Ia89ed4412a00601022c1fc94f046056ce4820fe8
BUG: 980838
Signed-off-by: Krishnan Parthasarathi <kparthas@redhat.com>
Reviewed-on: http://review.gluster.org/5262
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>