powerpc/dma: implement new dma_*map*_attrs() interfaces

Update powerpc to use the new dma_*map*_attrs() interfaces. In doing so
update struct dma_mapping_ops to accept a struct dma_attrs and propagate
these changes through to all users of the code (generic IOMMU and the
64bit DMA code, and the iseries and ps3 platform code).

The old dma_*map_*() interfaces are reimplemented as calls to the
corresponding new interfaces.

Signed-off-by: Mark Nelson <markn@au1.ibm.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Geoff Levand <geoffrey.levand@am.sony.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>