quotad: Remove dead code

        Backport of http://review.gluster.org/8180

client_t is created by server xlator for managing connection related
resources. Quotad doesn't do that. So no need to handle anything related
to it.

BUG: 1113403
Change-Id: I4f457b60c0b3377f8980857a883da1cf3e44d16e
Signed-off-by: Pranith Kumar K <pkarampu@redhat.com>
Reviewed-on: http://review.gluster.org/8227
Reviewed-by: Krutika Dhananjay <kdhananj@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Niels de Vos <ndevos@redhat.com>