dma-mapping: fix debug print to display correct dma_pfn_offset

fix the dev_dbg to display the offset which is the calculated
dma_pfn_offset value and set later in the code.
Signed-off-by: Murali Karicheri <m-karicheri2@ti.com>
Signed-off-by: Rob Herring <robh@kernel.org>

drivers/of/platform.c

@@ -188,7 +188,7 @@ static void of_dma_configure(struct device *dev)
 		size = dev->coherent_dma_mask;
 	} else {
 		offset = PFN_DOWN(paddr - dma_addr);
-		dev_dbg(dev, "dma_pfn_offset(%#08lx)\n", dev->dma_pfn_offset);
+		dev_dbg(dev, "dma_pfn_offset(%#08lx)\n", offset);
 	}
 	dev->dma_pfn_offset = offset;