Use ACPI "_RST" method to reset the controller, since FLR is not
supported.

Function hisi_sas_stop_phys() is introduced to remove some code
duplication.
Signed-off-by: NXiang Chen <chenxiang66@hisilicon.com>
Signed-off-by: NJohn Garry <john.garry@huawei.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>