dht: fix a typo

Change-Id: Id6f156957e58aad06bf2602f880c7e4102b80fd1
BUG: 764890
Signed-off-by: JulesWang <w.jq0722@gmail.com>
Reviewed-on: http://review.gluster.org/4679
Reviewed-by: Jeff Darcy <jdarcy@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>