scsi: hisi_sas: Don't check .nr_hw_queues in hisi_sas_task_prep()

Now that v2 and v3 hw expose their HW queues (and so shost.nr_hw_queues is
set), remove the conditional checks in hisi_sas_task_prep().

This change would affect v1 HW performance (as it does not expose HW
queues), but nobody uses it and support may be dropped soon.

Link: https://lore.kernel.org/r/1611659068-131975-3-git-send-email-john.garry@huawei.com
Reviewed-by: Xiang Chen <chenxiang66@hisilicon.com>
Signed-off-by: John Garry <john.garry@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>