cluster/dht: Changed log level to DEBUG

Change-Id: I7a4ee0c5a6a94bd4f31aff510a2971750913ed45
BUG: 1138602
Signed-off-by: Venkatesh Somyajulu <vsomyaju@redhat.com>
Reviewed-on: http://review.gluster.org/8621
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Xavier Hernandez <xhernandez@datalab.es>
Reviewed-by: susant palai <spalai@redhat.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>