We should first do the le16_to_cpu endian conversion and then apply the
FCP_CMD_LENGTH_MASK mask.

Fixes: 5f35509d ("qla2xxx: Terminate exchange if corrupted")
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Acked-by: NQuinn Tran <Quinn.Tran@cavium.com>
Acked-by: NHimanshu Madhani <himanshu.madhani@cavium.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>