swiotlb: remove swiotlb_dma_supported

The only user left is powerpc, but even there the generic dma-direct
version works just as well, given that we guarantee that the swiotlb
buffer must always be addressable.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Christian Zigotzky <chzigotzky@xenosoft.de>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/kernel/dma-swiotlb.c

@@ -36,7 +36,7 @@ const struct dma_map_ops powerpc_swiotlb_dma_ops = {
 	.free = __dma_nommu_free_coherent,
 	.map_sg = dma_direct_map_sg,
 	.unmap_sg = dma_direct_unmap_sg,
-	.dma_supported = swiotlb_dma_supported,
+	.dma_supported = dma_direct_supported,
 	.map_page = dma_direct_map_page,
 	.unmap_page = dma_direct_unmap_page,
 	.sync_single_for_cpu = dma_direct_sync_single_for_cpu,