MIPS: remove a dead ifdef from mach-ath25/dma-coherence.h

ath25 is alwas non-coherent, so keeping these ifdefs doesn't make any sense.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Paul Burton <paul.burton@mips.com>
Patchwork: https://patchwork.linux-mips.org/patch/19528/Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: David Daney <david.daney@cavium.com>
Cc: Kevin Cernekee <cernekee@gmail.com>
Cc: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: Tom Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Huacai Chen <chenhc@lemote.com>
Cc: iommu@lists.linux-foundation.org
Cc: linux-mips@linux-mips.org

arch/mips/include/asm/mach-ath25/dma-coherence.h

@@ -61,12 +61,7 @@ static inline int plat_dma_supported(struct device *dev, u64 mask)
 
 static inline int plat_device_is_coherent(struct device *dev)
 {
-#ifdef CONFIG_DMA_COHERENT
-	return 1;
-#endif
-#ifdef CONFIG_DMA_NONCOHERENT
 	return 0;
-#endif
 }
 
 static inline void plat_post_dma_flush(struct device *dev)