powerpc/dma: use the generic direct mapping bypass

Now that we've switched all the powerpc nommu and swiotlb methods to
use the generic dma_direct_* calls we can remove these ops vectors
entirely and rely on the common direct mapping bypass that avoids
indirect function calls entirely.  This also allows to remove a whole
lot of boilerplate code related to setting up these operations.

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/platforms/pseries/vio.c

@@ -1699,3 +1699,10 @@ int vio_disable_interrupts(struct vio_dev *dev)
 }
 EXPORT_SYMBOL(vio_disable_interrupts);
 #endif /* CONFIG_PPC_PSERIES */
+
+static int __init vio_init(void)
+{
+	dma_debug_add_bus(&vio_bus_type);
+	return 0;
+}
+fs_initcall(vio_init);