PCI: use pci_is_root_bus() in pci_read_bridge_bases()

Use pci_is_root_bus() in pci_read_bridge_bases() to check if the pci
bus is root, for code consistency.
Reviewed-by: NAlex Chiang <achiang@hp.com>
Reviewed-by: NGrant Grundler <grundler@parisc-linux.org>
Signed-off-by: NKenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>

drivers/pci/probe.c

@@ -289,7 +289,7 @@ void __devinit pci_read_bridge_bases(struct pci_bus *child)
 	struct resource *res;
 	int i;
 
-	if (!child->parent)	/* It's a host bus, nothing to read */
+	if (pci_is_root_bus(child))	/* It's a host bus, nothing to read */
 		return;
 
 	if (dev->transparent) {