x86: make dev_to_node return online node

a numa system (with multi HT chains) may return node without ram. Aka it
is not online. Try to get an online node, otherwise return -1.
Signed-off-by: NYinghai Lu <yinghai.lu@sun.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

arch/x86/pci/acpi.c

@@ -172,6 +172,9 @@ struct pci_bus * __devinit pci_acpi_scan_root(struct acpi_device *device, int do
 		set_mp_bus_to_node(busnum, node);
 	else
 		node = get_mp_bus_to_node(busnum);
+
+	if (node != -1 && !node_online(node))
+		node = -1;
 #endif
 
 	/* Allocate per-root-bus (not per bus) arch-specific data.