dma-mapping: remove an outdated comment from dma-map-ops.h

The "/* CONFIG_ARCH_HAS_DMA_COHERENCE_H */" was an description about the
ARCH_HAS_DMA_COHERENCE_H configure option, but it has been removed since
the dma_default_coherent variable was lifted from the mips architecture
to the driver core. Therefore it doesn't match any compile guard now.
Just remove it.

Fixes: 6d4e9a8 ("driver core: lift dma_default_coherent into common code")
Signed-off-by: Sui Jingfeng <[email protected]>
Signed-off-by: Christoph Hellwig <[email protected]>

Author: suijingfeng

include/linux/dma-map-ops.h

@@ -242,7 +242,7 @@ static inline bool dev_is_dma_coherent(struct device *dev)
 {
 	return true;
 }
-#endif /* CONFIG_ARCH_HAS_DMA_COHERENCE_H */
+#endif
 
 static inline void dma_reset_need_sync(struct device *dev)
 {