of: Provide default of_node_to_nid() implementation.

of_node_to_nid() is only relevant in a few architectures.  Don't force
everyone to implement it anyway.

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
diff --git a/arch/powerpc/include/asm/prom.h b/arch/powerpc/include/asm/prom.h
index da7dd63..55bccc0 100644
--- a/arch/powerpc/include/asm/prom.h
+++ b/arch/powerpc/include/asm/prom.h
@@ -103,6 +103,13 @@
 /* Get the MAC address */
 extern const void *of_get_mac_address(struct device_node *np);
 
+#ifdef CONFIG_NUMA
+extern int of_node_to_nid(struct device_node *device);
+#else
+static inline int of_node_to_nid(struct device_node *device) { return 0; }
+#endif
+#define of_node_to_nid of_node_to_nid
+
 /**
  * of_irq_map_pci - Resolve the interrupt for a PCI device
  * @pdev:	the device whose interrupt is to be resolved
diff --git a/arch/powerpc/include/asm/topology.h b/arch/powerpc/include/asm/topology.h
index 32adf72..09dd38c 100644
--- a/arch/powerpc/include/asm/topology.h
+++ b/arch/powerpc/include/asm/topology.h
@@ -41,8 +41,6 @@
 			       cpu_all_mask :				\
 			       node_to_cpumask_map[node])
 
-int of_node_to_nid(struct device_node *device);
-
 struct pci_bus;
 #ifdef CONFIG_PCI
 extern int pcibus_to_node(struct pci_bus *bus);
@@ -94,11 +92,6 @@
 
 #else
 
-static inline int of_node_to_nid(struct device_node *device)
-{
-	return 0;
-}
-
 static inline void dump_numa_cpu_topology(void) {}
 
 static inline int sysfs_add_device_to_node(struct sys_device *dev, int nid)