Fix a typo in hisi_sas_task_prep().

Fixes: 7eee4b92 ("scsi: hisi_sas: relocate smp sg map")
Signed-off-by: NWei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>