xen/arm: use dma-noncoherent.h calls for xen-swiotlb cache maintainance

Copy the arm64 code that uses the dma-direct/swiotlb helpers for DMA
on-coherent devices.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>

arch/arm/mm/dma-mapping.c

@@ -1105,10 +1105,6 @@ static const struct dma_map_ops *arm_get_dma_map_ops(bool coherent)
 	 * 32-bit DMA.
 	 * Use the generic dma-direct / swiotlb ops code in that case, as that
 	 * handles bounce buffering for us.
-	 *
-	 * Note: this checks CONFIG_ARM_LPAE instead of CONFIG_SWIOTLB as the
-	 * latter is also selected by the Xen code, but that code for now relies
-	 * on non-NULL dev_dma_ops.  To be cleaned up later.
 	 */
 	if (IS_ENABLED(CONFIG_ARM_LPAE))
 		return NULL;
@@ -2318,10 +2314,8 @@ void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
 	set_dma_ops(dev, dma_ops);
 
 #ifdef CONFIG_XEN
-	if (xen_initial_domain()) {
-		dev->archdata.dev_dma_ops = dev->dma_ops;
+	if (xen_initial_domain())
 		dev->dma_ops = xen_dma_ops;
-	}
 #endif
 	dev->archdata.dma_ops_setup = true;
 }