scsi: dma-mapping: always provide dma_get_cache_alignment

Provide the dummy version of dma_get_cache_alignment that always returns
1 even if CONFIG_HAS_DMA is not set, so that drivers and subsystems can
use it without ifdefs.

Cc: stable@vger.kernel.org
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

include/linux/dma-mapping.h

@@ -710,15 +710,13 @@ static inline void *dma_zalloc_coherent(struct device *dev, size_t size,
 	return ret;
 }
 
-#ifdef CONFIG_HAS_DMA
 static inline int dma_get_cache_alignment(void)
 {
 #ifdef ARCH_DMA_MINALIGN
 	return ARCH_DMA_MINALIGN;
 #endif
 	return 1;
 }
-#endif
 
 /* flags for the coherent memory api */
 #define DMA_MEMORY_EXCLUSIVE		0x01