[libata] improve device scan

Replace SCSI's legacy "bang at the door" method of probing with one
directly controlled by the underlying ATA transport layer.

We now only call scsi_scan_target() for devices we find, rather than
probing every possible channel/id within a certain range.
diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c
index e5b0199..902c763 100644
--- a/drivers/scsi/libata-core.c
+++ b/drivers/scsi/libata-core.c
@@ -4113,7 +4113,7 @@
 	for (i = 0; i < count; i++) {
 		struct ata_port *ap = host_set->ports[i];
 
-		scsi_scan_host(ap->host);
+		ata_scsi_scan_host(ap);
 	}
 
 	dev_set_drvdata(dev, host_set);