TARGET_SCF_LOOKUP_LUN_FROM_TAG is no longer used so remove it.

Link: https://lore.kernel.org/r/1604257174-4524-5-git-send-email-michael.christie@oracle.comReviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>