PCI: Clean up usages of pci_bus->is_added

Now pci_bus->is_added is only used to guard invoking of
pcibios_fixup_bus() in pci_scan_child_bus(), so just set
it directly after the fixups and remove the other test
and set in pci_bus_add_devices().

[bhelgaas: changelog]
Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Yinghai Lu <yinghai@kernel.org>
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index b494066..45c93b3 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1627,8 +1627,7 @@
 	if (!bus->is_added) {
 		dev_dbg(&bus->dev, "fixups for bus\n");
 		pcibios_fixup_bus(bus);
-		if (pci_is_root_bus(bus))
-			bus->is_added = 1;
+		bus->is_added = 1;
 	}
 
 	for (pass=0; pass < 2; pass++)