powerpc: Remove swiotlb_pci_dma_ops

Now swiotlb_pci_dma_ops is identical to swiotlb_dma_ops; we can use
swiotlb_dma_ops with any devices. This removes swiotlb_pci_dma_ops.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Acked-by: Becky Bruce <beckyb@kernel.crashing.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>