openrisc: remove arch-specific dma_supported implementation

This implementation is simply bogus - openrisc only has a simple
direct mapped DMA implementation and thus doesn't care about the
address.
Signed-off-by: Christoph Hellwig <hch@lst.de>

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

@@ -33,11 +33,4 @@ static inline const struct dma_map_ops *get_arch_dma_ops(struct bus_type *bus)
 	return &or1k_dma_map_ops;
 }
 
-#define HAVE_ARCH_DMA_SUPPORTED 1
-static inline int dma_supported(struct device *dev, u64 dma_mask)
-{
-	/* Support 32 bit DMA mask exclusively */
-	return dma_mask == DMA_BIT_MASK(32);
-}
-
 #endif	/* __ASM_OPENRISC_DMA_MAPPING_H */