xen-swiotlb: remove xen_swiotlb_set_dma_mask

This just duplicates the generic implementation.
Signed-off-by: Christoph Hellwig <hch@lst.de>

drivers/xen/swiotlb-xen.c

@@ -661,17 +661,6 @@ xen_swiotlb_dma_supported(struct device *hwdev, u64 mask)
 	return xen_virt_to_bus(xen_io_tlb_end - 1) <= mask;
 }
 
-static int
-xen_swiotlb_set_dma_mask(struct device *dev, u64 dma_mask)
-{
-	if (!dev->dma_mask || !xen_swiotlb_dma_supported(dev, dma_mask))
-		return -EIO;
-
-	*dev->dma_mask = dma_mask;
-
-	return 0;
-}
-
 /*
  * Create userspace mapping for the DMA-coherent memory.
  * This function should be called with the pages from the current domain only,
@@ -734,7 +723,6 @@ const struct dma_map_ops xen_swiotlb_dma_ops = {
 	.map_page = xen_swiotlb_map_page,
 	.unmap_page = xen_swiotlb_unmap_page,
 	.dma_supported = xen_swiotlb_dma_supported,
-	.set_dma_mask = xen_swiotlb_set_dma_mask,
 	.mmap = xen_swiotlb_dma_mmap,
 	.get_sgtable = xen_swiotlb_get_sgtable,
 	.mapping_error	= xen_swiotlb_mapping_error,