The enclosure_add_device() function should fail if it can't create the
relevant sysfs links.

Cc: <stable@vger.kernel.org>
Signed-off-by: Maurizio Lombardi <mlombard@redhat.com>
Tested-by: Douglas Miller <dougmill@linux.vnet.ibm.com>
Acked-by: James Bottomley <jejb@linux.vnet.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>