cluster/dht: stack wind with cookie

Default_fops uses stack_wind_tail. It winds without creating the frame leading
into wrong subvol return in the cookie. To avoid the problem caused by the
same, we're getting the subvol by passing the cookie.

Change-Id: I51ee79b22c89e4fb0b89e9a0bc3ac96c5b469f8f
BUG: 893338
Signed-off-by: Varun Shastry <vshastry@redhat.com>
Reviewed-on: http://review.gluster.org/4388
Reviewed-by: Jeff Darcy <jdarcy@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Anand Avati <avati@redhat.com>
Tested-by: Anand Avati <avati@redhat.com>