dma-mapping: move dma_mark_clean to dma-direct.h

And unlike the other helpers we don't require a <asm/dma-direct.h> as
this helper is a special case for ia64 only, and this keeps it as
simple as possible.

Signed-off-by: Christoph Hellwig <hch@lst.de>

arch/unicore32/include/asm/dma-mapping.h

@@ -25,7 +25,5 @@ static inline const struct dma_map_ops *get_arch_dma_ops(struct bus_type *bus)
 	return &swiotlb_dma_map_ops;
 }
 
-static inline void dma_mark_clean(void *addr, size_t size) {}
-
 #endif /* __KERNEL__ */
 #endif