locks: fix leaking entrylk lock structure

When entrylk lock requests are blocked and granted aysnchronously,
the entrylk lock structure was getting leaked.

Change-Id: Ie3f29f550730189f27745d991b029e50c63e63da
BUG: 962350
Signed-off-by: Anand Avati <avati@redhat.com>
Reviewed-on: http://review.gluster.org/4991
Reviewed-by: Krishnan Parthasarathi <kparthas@redhat.com>
Reviewed-by: Pranith Kumar Karampuri <pkarampu@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>