lvm: remove unused add/remove tags

Change-Id: Ibffb9138cb28e150f18e2283c24a60c165cde337
Signed-off-by: Yeela Kaplan <ykaplan@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/25013
Reviewed-by: Dan Kenigsberg <danken@redhat.com>
Reviewed-by: Douglas Schilling Landgraf <dougsland@redhat.com>
Reviewed-by: Federico Simoncelli <fsimonce@redhat.com>