scsi: provide a generic change_queue_type method

Most drivers use exactly the same implementation, so provide it as a
library function.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Mike Christie <michaelc@cs.wisc.edu>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
index 238e06f..7bcace2 100644
--- a/drivers/scsi/scsi_debug.c
+++ b/drivers/scsi/scsi_debug.c
@@ -4532,14 +4532,7 @@
 static int
 sdebug_change_qtype(struct scsi_device *sdev, int qtype)
 {
-	if (sdev->tagged_supported) {
-		scsi_set_tag_type(sdev, qtype);
-		if (qtype)
-			scsi_activate_tcq(sdev, sdev->queue_depth);
-		else
-			scsi_deactivate_tcq(sdev, sdev->queue_depth);
-	} else
-		qtype = 0;
+	qtype = scsi_change_queue_type(sdev, qtype);
 	if (SCSI_DEBUG_OPT_Q_NOISE & scsi_debug_opts) {
 		const char *cp;