rbd: return FailedPrecondition error message
rbd: return FailedPrecondition error message

In case of the DR the image on the primary site cannot be
demoted as the cluster is down, during failover the image need
to be force promoted. RBD returns `Device or resource busy`
error message if the image cannot be promoted for above reason.
Return FailedPrecondition so that replication operator can send
request to force promote the image.

Signed-off-by: Madhu Rajanna <60fbf37a92c2a0908e31296d18dadbec5a4dae17@gmail.com>

ceph/ceph-csi,ceph/ceph-csi,ceph/ceph-csi,ceph/ceph-csi