The tcmu dev is added to the list of tcmu devices during configuration.  At
this time the tcmu setup has completed, but lio core has not completed its
setup. The device is not yet usable so do not try to unmap blocks from it
Signed-off-by: NMike Christie <mchristi@redhat.com>
Reviewed-by: NXiubo Li <xiubli@redhat.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>