scsi: set REQ_QUEUE for the blk-mq case

To generate the right SPI tag messages we need to properly set
QUEUE_FLAG_QUEUED in the request_queue and mirror it to the
request.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Jens Axboe <axboe@kernel.dk>
Reported-by: Meelis Roos <mroos@linux.ee>
Tested-by: Meelis Roos <mroos@linux.ee>
Cc: stable@vger.kernel.org