cell: fix spu/nid placement in 2.6.16 SDK kernel

The of_node_to_nid() function originally depended on of_node_numa_domain
to return -1 if no nid was found for a node - this wasn't the case in
2.6.16, where there's no distinction between "no nid" and nid 0

Change of_node_to_nid() to check for the ibm,associativity property
itself.

Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>

Index: linus-2.6/arch/powerpc/mm/numa.c
===================================================================
--- linus-2.6.orig/arch/powerpc/mm/numa.c
+++ linus-2.6/arch/powerpc/mm/numa.c
@@ -216,9 +216,11 @@ int of_node_to_nid(struct device_node *d
 
 	of_node_get(device);
 	while (device) {
-		nid = of_node_numa_domain(device);
-		if (nid != -1)
+		unsigned int *assoc = of_get_associativity(device);
+		if (assoc && *assoc >= min_common_depth) {
+			nid = assoc[min_common_depth];
 			break;
+		}
 
 	        tmp = device;
 		device = of_get_parent(tmp);