ARM/dma-mapping: remove the unused virt_to_dma helper

virt_to_dma was only used by the now removed dmabounce code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Tested-by: Marc Zyngier <maz@kernel.org>

arch/arm/include/asm/dma-direct.h

@@ -5,7 +5,7 @@
 #include <asm/memory.h>
 
 /*
- * dma_to_pfn/pfn_to_dma/virt_to_dma are architecture private
+ * dma_to_pfn/pfn_to_dma are architecture private
  * functions used internally by the DMA-mapping API to provide DMA
  * addresses. They must not be used by drivers.
  */
@@ -25,14 +25,6 @@ static inline unsigned long dma_to_pfn(struct device *dev, dma_addr_t addr)
 	return pfn;
 }
 
-static inline dma_addr_t virt_to_dma(struct device *dev, void *addr)
-{
-	if (dev)
-		return pfn_to_dma(dev, virt_to_pfn(addr));
-
-	return (dma_addr_t)__virt_to_bus((unsigned long)(addr));
-}
-
 static inline dma_addr_t phys_to_dma(struct device *dev, phys_addr_t paddr)
 {
 	unsigned int offset = paddr & ~PAGE_MASK;