scsi: libsas: Introduce sas_find_attached_phy_id() helper

LLDDs are all implementing their own attached phy ID finding code.  Factor
it out to libsas.

Signed-off-by: Jason Yan <yanaijie@huawei.com>
Link: https://lore.kernel.org/r/20220928070130.3657183-3-yanaijie@huawei.com


Reviewed-by: Jack Wang <jinpu.wang@ionos.com>
Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Reviewed-by: John Garry <john.garry@huawei.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>