ia64: add dma_capable() to replace is_buffer_dma_capable()

dma_capable() eventually replaces is_buffer_dma_capable(), which tells
if a memory area is dma-capable or not. The problem of
is_buffer_dma_capable() is that it doesn't take a pointer to struct
device so it doesn't work for POWERPC.
Signed-off-by: NFUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>

arch/ia64/include/asm/dma-mapping.h

@@ -69,6 +69,14 @@ dma_set_mask (struct device *dev, u64 mask)
 	return 0;
 }
 
+static inline bool dma_capable(struct device *dev, dma_addr_t addr, size_t size)
+{
+	if (!dev->dma_mask)
+		return 0;
+
+	return addr + size <= *dev->dma_mask;
+}
+
 extern int dma_get_cache_alignment(void);
 
 static inline void