Fix logging if the rbd manager command is supported
Fix logging if the rbd manager command is supported

if there is an error when adding the rbd task
we are logging the output which is empty. This
PR logs the error if the rbd task is supported
and there is an error.

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

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