powerpc/cell: Don't use flat device-tree after boot

Some bit of SPU code was using the FDT rather than the expanded
device-tree. Fix it.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/platforms/cell/spu_manage.c

@@ -535,8 +535,7 @@ static int __init init_affinity(void)
 	if (of_has_vicinity()) {
 		init_affinity_fw();
 	} else {
-		long root = of_get_flat_dt_root();
-		if (of_flat_dt_is_compatible(root, "IBM,CPBW-1.0"))
+		if (of_machine_is_compatible("IBM,CPBW-1.0"))
 			init_affinity_qs20_harcoded();
 		else
 			printk("No affinity configuration found\n");