powerpc: Drop archdata numa_node

Use the struct device's numa_node instead; use accessor functions
to get/set numa_node.

Signed-off-by: Becky Bruce <becky.bruce@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
diff --git a/arch/powerpc/kernel/dma-iommu.c b/arch/powerpc/kernel/dma-iommu.c
index 01091f1..49248f8 100644
--- a/arch/powerpc/kernel/dma-iommu.c
+++ b/arch/powerpc/kernel/dma-iommu.c
@@ -20,7 +20,7 @@
 {
 	return iommu_alloc_coherent(dev, dev->archdata.dma_data, size,
 				    dma_handle, device_to_mask(dev), flag,
-				    dev->archdata.numa_node);
+				    dev_to_node(dev));
 }
 
 static void dma_iommu_free_coherent(struct device *dev, size_t size,