scsi: hisi_sas: Implement handlers of PCIe FLR for v3 hw

This patch implements handlers of PCIe FLR for v3 hw, reset_prepare() and
reset_done().

User can issue FLR through sysfs interface, as v3 hw support PCIe FLR.
Then if we don't implement these two handlers, our SAS controller will not
work after executing FLR.

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