scsi: core: Move the definition of SCSI_QUEUE_DELAY

Move the definition of SCSI_QUEUE_DELAY to just above the function that
uses it.

Link: https://lore.kernel.org/r/20220630195703.10155-2-bvanassche@acm.org
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: John Garry <john.garry@huawei.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>