scsi: scsi_transport_sas: switch to SPDX tags

Use the the GPLv2 SPDX tag instead of a free form blurb.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/scsi_transport_sas.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2005-2006 Dell Inc.
- *	Released under GPL v2.
  *
  * Serial Attached SCSI (SAS) transport class.
  *