powerpc: remove unused swiotlb_phys_to_bus() and swiotlb_bus_to_phys()

phys_to_dma() and dma_to_phys() are used instead of
swiotlb_phys_to_bus() and swiotlb_bus_to_phys().
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Acked-by: Becky Bruce <beckyb@kernel.crashing.org>

arch/powerpc/kernel/dma-swiotlb.c

@@ -24,17 +24,6 @@
 int swiotlb __read_mostly;
 unsigned int ppc_swiotlb_enable;
 
-dma_addr_t swiotlb_phys_to_bus(struct device *hwdev, phys_addr_t paddr)
-{
-	return paddr + get_dma_direct_offset(hwdev);
-}
-
-phys_addr_t swiotlb_bus_to_phys(struct device *hwdev, dma_addr_t baddr)
-
-{
-	return baddr - get_dma_direct_offset(hwdev);
-}
-
 /*
  * Determine if an address is reachable by a pci device, or if we must bounce.
  */