ceph-config: don't check for devices on existing osds
ceph-config: don't check for devices on existing osds

When osd_auto_discovery is true the `devices` var will be empty (as the disks have holders).
Also in general there is no need to check for devices to list the devices with ceph-volume as we have `default({})` on the stdout in `num_osds` set fact in the next task

Signed-off-by: Seena Fallah <367913d4df628ad6321bda291c1f2d6ae5e2f066@gmail.com>

ceph/ceph-ansible,ceph/ceph-ansible