x86: convert dma_alloc_coherent to use is_device_dma_capable

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/include/asm-x86/dma-mapping.h b/include/asm-x86/dma-mapping.h
index f43420b..f408e6d 100644
--- a/include/asm-x86/dma-mapping.h
+++ b/include/asm-x86/dma-mapping.h
@@ -278,7 +278,7 @@
 		gfp |= GFP_DMA;
 	}
 
-	if (!dev->dma_mask)
+	if (!is_device_dma_capable(dev))
 		return NULL;
 
 	if (!ops->alloc_coherent)