x86, numaq: add pci_acpi_scan_root() stub

allow 32-bit numaq build to succeed with ACPI enabled.

arch/x86/kernel/numaq_32.c

@@ -87,3 +87,14 @@ static int __init numaq_tsc_disable(void)
 	return 0;
 }
 arch_initcall(numaq_tsc_disable);
+
+#ifdef CONFIG_ACPI
+/*
+ * Dummy implementation:
+ */
+struct pci_bus * __devinit
+pci_acpi_scan_root(struct acpi_device *device, int domain, int busnum)
+{
+	return NULL;
+}
+#endif