scsi: hisi_sas: handle PHY UP+DOWN simultaneous irq

Handle the situation that PHY UP and DOWN irq happen simultaneously.
There is no mechanism of SoC HW to ensure this situation will never
happen. So, we add this handle just in case.

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>