[POWERPC] Add celleb_dma_dev_setup()

Celleb always uses dma_direct_ops, and sets dma_direct_offset, so it
too should set dma_data to dma_direct_offset.

Currently there's no pci_dma_dev_setup() routine for Celleb so add one.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>