scsi: target: spc: Fix RSOC parameter data header size

[ Upstream commit b5053231 ]

The SPC document states that "The COMMAND DATA LENGTH field indicates the
length in bytes of the command descriptor list".

The length should be subtracted by 4 to represent the length of the
description list, not 3.

Signed-off-by: Chaohai Chen <wdhh66@163.com>
Link: https://lore.kernel.org/r/20250115070739.216154-1-wdhh66@163.com


Reviewed-by: Dmitry Bogdanov <d.bogdanov@yadro.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>