rados: add an error to be used if data is requested too early
rados: add an error to be used if data is requested too early

Add a new error that will be returned from a op step method if the
method is called before the step is ready to provide data - like
when the operation has not yet been performed.

Signed-off-by: John Mulligan <eda8ad33169deab44f9fe65847f99e368da6c91b@redhat.com>

ceph/go-ceph,ceph/go-ceph,ceph/go-ceph