dma: Add set_dma_mask hook to struct dma_map_ops

POWERPC needs this hook. SPARC could use it too.
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Acked-by: Becky Bruce <beckyb@kernel.crashing.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

include/linux/dma-mapping.h

@@ -58,6 +58,7 @@ struct dma_map_ops {
 				   enum dma_data_direction dir);
 	int (*mapping_error)(struct device *dev, dma_addr_t dma_addr);
 	int (*dma_supported)(struct device *dev, u64 mask);
+	int (*set_dma_mask)(struct device *dev, u64 mask);
 	int is_phys;
 };