ARM: dma-mapping: Small logical clean up

Skip unnecessary operations if order == 0. A little bit easier to
read.

Signed-off-by: Hiroshi Doyu <hdoyu@nvidia.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index 13f555d..c390cea 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -1012,11 +1012,12 @@
 		if (!pages[i])
 			goto error;
 
-		if (order)
+		if (order) {
 			split_page(pages[i], order);
-		j = 1 << order;
-		while (--j)
-			pages[i + j] = pages[i] + j;
+			j = 1 << order;
+			while (--j)
+				pages[i + j] = pages[i] + j;
+		}
 
 		__dma_clear_buffer(pages[i], PAGE_SIZE << order);
 		i += 1 << order;