scsi: remove MSG_*_TAG defines

For SPI drivers use the message definitions from scsi.h, and for target
drivers introduce a new TCM_*_TAG namespace.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com
diff --git a/drivers/target/target_core_pscsi.c b/drivers/target/target_core_pscsi.c
index 7c8291f..caf03d5 100644
--- a/drivers/target/target_core_pscsi.c
+++ b/drivers/target/target_core_pscsi.c
@@ -1094,7 +1094,7 @@
 	req->retries = PS_RETRY;
 
 	blk_execute_rq_nowait(pdv->pdv_sd->request_queue, NULL, req,
-			(cmd->sam_task_attr == MSG_HEAD_TAG),
+			(cmd->sam_task_attr == TCM_HEAD_TAG),
 			pscsi_req_done);
 
 	return 0;