mgmt/glusterd: do not restart nfs server when snapshot is deactivated

Change-Id: Ie5eaa2beb4446640b22873f91e17da90d1cd8fad
BUG: 1174625
Signed-off-by: Raghavendra Bhat <raghavendra@redhat.com>
Reviewed-on: http://review.gluster.org/9280
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Kaushal M <kaushal@redhat.com>