dm: pci: Correct bus number when scanning sub-buses

The sub-bus passed to pciauto_prescan_setup_bridge() is incorrect. Fix it
so that sub-buses are numbered correctly.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/pci/pci-uclass.c b/drivers/pci/pci-uclass.c
index 41d19cb..edec93f 100644
--- a/drivers/pci/pci-uclass.c
+++ b/drivers/pci/pci-uclass.c
@@ -334,7 +334,7 @@
 
 	sub_bus = pci_get_bus_max() + 1;
 	debug("%s: bus = %d/%s\n", __func__, sub_bus, bus->name);
-	pciauto_prescan_setup_bridge(hose, bdf, bus->seq);
+	pciauto_prescan_setup_bridge(hose, bdf, sub_bus);
 
 	ret = device_probe(bus);
 	if (ret) {