scsi: mvsas: Fix dma_unmap_sg() nents value

scsi: mvsas: Fix dma_unmap_sg() nents value

[ Upstream commit 0141618727bc929fe868153d21797f10ce5bef3f ]

The dma_unmap_sg() functions should be called with the same nents as the
dma_map_sg(), not the value the map function returned.

Fixes: b5762948263d ("[SCSI] mvsas: Add Marvell 6440 SAS/SATA driver")
Signed-off-by: Thomas Fourier <fourier.thomas@gmail.com>
Link: https://lore.kernel.org/r/20250627134822.234813-2-fourier.thomas@gmail.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>