use generic DMA mapping code in powerpc V4

[Christoph Hellwig]

Hi Christian,

happy new year and I hope you had a few restful deays off.

I've pushed a new tree to:

   git://git.infradead.org/users/hch/misc.git powerpc-dma.6

Gitweb:

   http://git.infradead.org/users/hch/misc.git/shortlog/refs/heads/powerpc-dma.6

Which has been rebased to the latests Linus tree, which has a lot of
changes, and has also changed the patch split a bit to aid bisection.

I think 

   http://git.infradead.org/users/hch/misc.git/commitdiff/c446404b041130fbd9d1772d184f24715cf2362f

might be a good commit to re-start testing, then bisecting up to the
last commit using git bisect.