Fix privatestorageops issue 278

Systemd sets soft limits by using a <soft:hard> range, see
https://github.com/systemd/systemd/pull/1994. We want soft
and hard limit to be the same, so we use the IMO defective
former behavior of setting the limit once and have systemd
set both. RedHat Bug 1351415 has more informatin about not
being able to set soft limits within the systemd config in
before https://bugzilla.redhat.com/show_bug.cgi?id=1351415