arc: fix arc_dma_sync_sg_for_{cpu,device}

These functions should perform the same functionality as calling
arc_dma_sync_single_for_{cpu,device} on each S/G list element.  Ensure
they actually do that by calling arc_dma_sync_single_for_{cpu,device}.
Otherwise we could be passing a different dir argument.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Alexey Brodkin <abrodkin@synopsys.com>
Acked-by: Vineet Gupta <vgupta@synopsys.com>

arch/arc/mm/dma.c

@@ -241,7 +241,7 @@ static void arc_dma_sync_sg_for_cpu(struct device *dev,
 	struct scatterlist *sg;
 
 	for_each_sg(sglist, sg, nelems, i)
-		_dma_cache_sync(sg_phys(sg), sg->length, dir);
+		arc_dma_sync_single_for_cpu(dev, sg_phys(sg), sg->length, dir);
 }
 
 static void arc_dma_sync_sg_for_device(struct device *dev,
@@ -252,7 +252,8 @@ static void arc_dma_sync_sg_for_device(struct device *dev,
 	struct scatterlist *sg;
 
 	for_each_sg(sglist, sg, nelems, i)
-		_dma_cache_sync(sg_phys(sg), sg->length, dir);
+		arc_dma_sync_single_for_device(dev, sg_phys(sg), sg->length,
+				dir);
 }
 
 static int arc_dma_supported(struct device *dev, u64 dma_mask)