scsi: don't set tagging state from scsi_adjust_queue_depth

Remove the tagged argument from scsi_adjust_queue_depth, and just let it
handle the queue depth.  For most drivers those two are fairly separate,
given that most modern drivers don't care about the SCSI "tagged" status
of a command at all, and many old drivers allow queuing of multiple
untagged commands in the driver.

Instead we start out with the ->simple_tags flag set before calling
->slave_configure, which is how all drivers actually looking at
->simple_tags except for one worke anyway.  The one other case looks
broken, but I've kept the behavior as-is for now.

Except for that we only change ->simple_tags from the ->change_queue_type,
and when rejecting a tag message in a single driver, so keeping this
churn out of scsi_adjust_queue_depth is a clear win.

Now that the usage of scsi_adjust_queue_depth is more obvious we can
also remove all the trivial instances in ->slave_alloc or ->slave_configure
that just set it to the cmd_per_lun default.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mike Christie <michaelc@cs.wisc.edu>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/ncr53c8xx.c

@@ -7997,10 +7997,7 @@ static int ncr53c8xx_slave_configure(struct scsi_device *device)
 	if (depth_to_use > MAX_TAGS)
 		depth_to_use = MAX_TAGS;
 
-	scsi_adjust_queue_depth(device,
-				(device->tagged_supported ?
-				 MSG_SIMPLE_TAG : 0),
-				depth_to_use);
+	scsi_adjust_queue_depth(device, depth_to_use);
 
 	/*
 	**	Since the queue depth is not tunable under Linux,