PCI: sparse warning (trivial)

Assigning zero where NULL should be used.
Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

drivers/pci/bus.c

@@ -56,7 +56,7 @@ void pci_bus_remove_resources(struct pci_bus *bus)
 	int i;
 
 	for (i = 0; i < PCI_BRIDGE_RESOURCE_NUM; i++)
-		bus->resource[i] = 0;
+		bus->resource[i] = NULL;
 
 	list_for_each_entry_safe(bus_res, tmp, &bus->resources, list) {
 		list_del(&bus_res->list);