rgw, cls_rgw: trim olh log functionality

Signed-off-by: Yehuda Sadeh <yehuda@redhat.com>
rgw: no need for init olh op (to squash probably)

Signed-off-by: Yehuda Sadeh <yehuda@redhat.com>
rgw: olh atomicity groundwork

still more to do

Signed-off-by: Yehuda Sadeh <yehuda@redhat.com>