scsi: libfcoe: switch to SPDX tags

Use the the GPLv2 SPDX tag instead of verbose boilerplate text.

[mkp: fixed comment syntax on *.c]

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>