[SCSI] libsas: drop sata port multiplier infrastructure

On the way to add a new sata_device field, noticed that libsas is
carrying port multiplier infrastructure that is explicitly disabled by
sas_discover_sata(). The aic94xx touches the unused port_no, so leave
that field in case there was some use for it.

Signed-off-by: Dan Williams <[e-mail]>
Signed-off-by: James Bottomley <[e-mail]>

drivers/scsi/libsas/sas_discover.c

···
 		INIT_LIST_HEAD(&dev->ex_dev.children);
 		mutex_init(&dev->ex_dev.cmd_mutex);
 		break;
-	case SATA_DEV:
-	case SATA_PM:
-	case SATA_PM_PORT:
-	case SATA_PENDING:
-		INIT_LIST_HEAD(&dev->sata_dev.children);
-		break;
 	default:
 		break;
 	}

include/scsi/libsas.h

···
         enum   ata_command_set command_set;
         struct smp_resp        rps_resp; /* report_phy_sata_resp */
         u8     port_no;        /* port number, if this is a PM (Port) */
-        struct list_head children; /* PM Ports if this is a PM */
 
 	struct ata_port *ap;
 	struct ata_host ata_host;