scsi: hisi_sas: Stop returning error code from slot_complete_vX_hw()

The error codes are never checked, stop returning them.

Link: https://lore.kernel.org/r/1589552025-165012-5-git-send-email-john.garry@huawei.com


Signed-off-by: John Garry <john.garry@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>