We never call hisi_sas_hw.slot_complete, so remove it.

Link: https://lore.kernel.org/r/1567774537-20003-9-git-send-email-john.garry@huawei.comSigned-off-by: Luo Jiaxing <luojiaxing@huawei.com>
Signed-off-by: John Garry <john.garry@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>