Re: use generic DMA mapping code in powerpc V4

[Christoph Hellwig]

Just as a warning:  this series now has some conflicts with the dma
mapping tree due to the ->mapping_error removal, and there might be
some bigger ones if the direct calls for the direct mapping code series
goes ahead.  None of them affect the early part of the series that do
not touch the actual dma_map_ops instances, though.