x86/PCI: Remove unused pci_root_bus

pci_root_bus is unused, so remove all references to it.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
diff --git a/arch/x86/pci/numaq_32.c b/arch/x86/pci/numaq_32.c
index 83e125b..00edfe6 100644
--- a/arch/x86/pci/numaq_32.c
+++ b/arch/x86/pci/numaq_32.c
@@ -152,7 +152,7 @@
 
 	raw_pci_ops = &pci_direct_conf1_mq;
 
-	pci_root_bus = pcibios_scan_root(0);
+	pcibios_scan_root(0);
 	if (num_online_nodes() > 1)
 		for_each_online_node(quad) {
 			if (quad == 0)