[PATCH] dma-mapping.h stubs fix

do { } while(0) is not a good imitation of function returning void;
use ((void)0) instead.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/asm-alpha/dma-mapping.h b/include/asm-alpha/dma-mapping.h
index 1919d72..75a1aff 100644
--- a/include/asm-alpha/dma-mapping.h
+++ b/include/asm-alpha/dma-mapping.h
@@ -41,9 +41,9 @@
 #define dma_map_single(dev, va, size, dir)	virt_to_phys(va)
 #define dma_map_page(dev, page, off, size, dir)	(page_to_pa(page) + off)
 
-#define dma_unmap_single(dev, addr, size, dir)	do { } while (0)
-#define dma_unmap_page(dev, addr, size, dir)	do { } while (0)
-#define dma_unmap_sg(dev, sg, nents, dir)	do { } while (0)
+#define dma_unmap_single(dev, addr, size, dir)	((void)0)
+#define dma_unmap_page(dev, addr, size, dir)	((void)0)
+#define dma_unmap_sg(dev, sg, nents, dir)	((void)0)
 
 #define dma_mapping_error(addr)  (0)