purge: only purge ceph partitions
purge: only purge ceph partitions

Prior to this change we were purging all the partitions on the device
when using the raw_journal_devices scenario.
This was breaking deployments where other partitions are used for other
purposes (ie: OS system).

Signed-off-by: Sébastien Han <62d754cc350e84d3b1c32ae79f976f5348e74a40@redhat.com>

jsaintrocc/ceph-ansible,font/ceph-ansible,WingkaiHo/ceph-ansible,WingkaiHo/ceph-ansible,guits/ceph-ansible,albertomurillo/ceph-ansible,bengland2/ceph-ansible,ceph/ceph-ansible,fgal/ceph-ansible,verdurin/ceph-ansible-1,bengland2/ceph-ansible,albertomurillo/ceph-ansible,jtaleric/ceph-ansible,jtaleric/ceph-ansible,guits/ceph-ansible,fgal/ceph-ansible,albertomurillo/ceph-ansible,travmi/ceph-ansible,WingkaiHo/ceph-ansible,font/ceph-ansible,ceph/ceph-ansible,jsaintrocc/ceph-ansible,verdurin/ceph-ansible-1,travmi/ceph-ansible