scsi: hisi_sas: Add function complete_v3_hw()

Put the work of processing cq slots in a separate function,
complete_v3_hw(), which can then be used by cq_thread_v3_hw() and other
functions when adding poll support.

Co-developed-by: John Garry <john.garry@huawei.com>
Signed-off-by: John Garry <john.garry@huawei.com>
Signed-off-by: Xiang Chen <chenxiang66@hisilicon.com>
Link: https://lore.kernel.org/r/1678169355-76215-2-git-send-email-chenxiang66@hisilicon.com


Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>