osd: bring backward compatibility with old Jewel images

osd: bring backward compatibility with old Jewel images

There was a huge resync from luminous to jewel in ceph-docker:
https://github.com/ceph/ceph-docker/pull/797

This change brought a new handy function to discover partitions tight to
an OSD. This function doesn't exist in the old image so the
ceph-osd-run.sh script breaks when trying to deploy Jewel OSD with that
old Jewel image version.

Signed-off-by: Sébastien Han <seb@redhat.com>
(cherry picked from commit 968ef04324e9064fcecfe88bc5464ad9c2673a13)
Signed-off-by: Sébastien Han <seb@redhat.com>