Add framework to register and unregister the host and expander phys with
SCSI Transport Layer (STL).

Link: https://lore.kernel.org/r/20220804131226.16653-6-sreekanth.reddy@broadcom.comReviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: Sreekanth Reddy <sreekanth.reddy@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>