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>
diff --git a/drivers/of/platform.c b/drivers/of/platform.c
index 5b33c6a..a54ec10 100644
--- a/drivers/of/platform.c
+++ b/drivers/of/platform.c
@@ -188,7 +188,7 @@
 		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;