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/mm/dma-noncoherent.c

@@ -152,8 +152,8 @@ static struct ppc_vm_region *ppc_vm_region_find(struct ppc_vm_region *head, unsi
  * Allocate DMA-coherent memory space and return both the kernel remapped
  * virtual and bus address for that space.
  */
-void *__dma_nommu_alloc_coherent(struct device *dev, size_t size,
-		dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs)
+void *arch_dma_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,
+		gfp_t gfp, unsigned long attrs)
 {
 	struct page *page;
 	struct ppc_vm_region *c;
@@ -254,7 +254,7 @@ void *__dma_nommu_alloc_coherent(struct device *dev, size_t size,
 /*
  * free a page as defined by the above mapping.
  */
-void __dma_nommu_free_coherent(struct device *dev, size_t size, void *vaddr,
+void arch_dma_free(struct device *dev, size_t size, void *vaddr,
 		dma_addr_t dma_handle, unsigned long attrs)
 {
 	struct ppc_vm_region *c;