ceph-osd: fix autodetection activation

ceph-osd: fix autodetection activation

Prior to this patch this activation sequence for autodetection was
always skipped because we were asking to activate on device without
partitions, which doesn't make sense.

We also fix the way we lookup for a device, since the data partition is
always numbered 1, we take the min element of the dict.

Closes: https://github.com/ceph/ceph-ansible/issues/1782
Signed-off-by: Sébastien Han <seb@redhat.com>
Signed-off-by: Guillaume Abrioux <gabrioux@redhat.com>