ceph_key: fix idempotency when no secret is passed
ceph_key: fix idempotency when no secret is passed

553584cbd0d014429e665f998776e8d198f72d2b introduced a regression when no
secret is passed, it overwrites the secret each time the task is run.

Signed-off-by: Guillaume Abrioux <30a9df5a0293a6108675377fa1673f7aa713f915@redhat.com>

ceph/ceph-ansible,ceph/ceph-ansible