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>

Documentation/scsi/scsi_mid_low_api.txt

@@ -271,9 +271,9 @@ init_this_scsi_driver() ----+
                       slave_destroy() ***
 ------------------------------------------------------------
 
-The mid level invokes scsi_adjust_queue_depth() with tagged queuing off and
-"cmd_per_lun" for that host as the queue length. These settings can be
-overridden by a slave_configure() supplied by the LLD.
+The mid level invokes scsi_adjust_queue_depth() with "cmd_per_lun" for that
+host as the queue length. These settings can be overridden by a
+slave_configure() supplied by the LLD.
 
 *** For scsi devices that the mid level tries to scan but do not
     respond, a slave_alloc(), slave_destroy() pair is called.
@@ -438,9 +438,6 @@ int scsi_add_host(struct Scsi_Host *shost, struct device * dev)
 /**
  * scsi_adjust_queue_depth - allow LLD to change queue depth on a SCSI device
  * @sdev:       pointer to SCSI device to change queue depth on
- * @tagged:     0 - no tagged queuing
- *              MSG_SIMPLE_TAG - simple tagged queuing
- *              MSG_ORDERED_TAG - ordered tagged queuing
  * @tags        Number of tags allowed if tagged queuing enabled,
  *              or number of commands the LLD can queue up
  *              in non-tagged mode (as per cmd_per_lun).
@@ -456,8 +453,7 @@ int scsi_add_host(struct Scsi_Host *shost, struct device * dev)
  *      Defined in: drivers/scsi/scsi.c [see source code for more notes]
  *
  **/
-void scsi_adjust_queue_depth(struct scsi_device * sdev, int tagged, 
-                             int tags)
+void scsi_adjust_queue_depth(struct scsi_device *sdev, int tags)
 
 
 /**