scsi: allow LLDDs to expose the queue mapping to blk-mq

Just hand through the blk-mq map_queues method in the host template.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index 7e4cd53..36680f1 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -278,6 +278,14 @@ struct scsi_host_template {
 	int (* change_queue_depth)(struct scsi_device *, int);
 
 	/*
+	 * This functions lets the driver expose the queue mapping
+	 * to the block layer.
+	 *
+	 * Status: OPTIONAL
+	 */
+	int (* map_queues)(struct Scsi_Host *shost);
+
+	/*
 	 * This function determines the BIOS parameters for a given
 	 * harddisk.  These tend to be numbers that are made up by
 	 * the host adapter.  Parameters: