scsi: never drop to untagged mode during queue ramp down
scsi: never drop to untagged mode during queue ramp down

Dropping to untagged mode when ramping down a queue due to QUEUE FULL
events has two problems:

 - nothing in the midlayer or drivers ever moves back to tagged mode
   during queue ramp up.
 - cmd_per_lun isn't the untagged queue depth for many modern drivers
   that can handle multiple untagged commands, and this is the only
   place in the midlayer assuming that.

Signed-off-by: Christoph Hellwig <923f7720577207a44b32e59bbfbea59d27f1ae8e@lst.de>
Reviewed-by: Bart Van Assche <89ed62d80e76c0eb24ee0d6433b48a91c2273b5e@acm.org>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com
Reviewed-by: Hannes Reinecke <b0d1e9e4a4e27620745ff49be9000da3174a4cc6@suse.de>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs