MIPS: ath25: Remove unused DMA helper functions.

These got merged with the ath25 support after 4e7f72660c39 (MIPS: Remove
unnecessary platform dma helper functions) had already removed them for
all other platforms.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/include/asm/mach-ath25/dma-coherence.h b/arch/mips/include/asm/mach-ath25/dma-coherence.h
index d8009c9..65084a0 100644
--- a/arch/mips/include/asm/mach-ath25/dma-coherence.h
+++ b/arch/mips/include/asm/mach-ath25/dma-coherence.h
@@ -59,16 +59,6 @@
 	return 1;
 }
 
-static inline void plat_extra_sync_for_device(struct device *dev)
-{
-}
-
-static inline int plat_dma_mapping_error(struct device *dev,
-					 dma_addr_t dma_addr)
-{
-	return 0;
-}
-
 static inline int plat_device_is_coherent(struct device *dev)
 {
 #ifdef CONFIG_DMA_COHERENT