use generic DMA mapping code in powerpc V4

[Christoph Hellwig]

On Wed, Dec 05, 2018 at 10:44:05AM +0100, Christian Zigotzky wrote:
> Thanks for your reply. I undid all dma mapping commits with the following 
> command:
>
> git checkout 721c01ba8b46ddb5355bd6e6b3bbfdabfdf01e97
>
> After that I compiled the kernels with this code for my P5020 board (Cyrus) 
> and for my PASEMI board (Nemo) today.
>
> Result: PASEMI onboard ethernet works again and the P5020 board boots.
>
> It seems the dma mapping commits are the problem.

Thanks.  Can you try a few stepping points in the tree?

First just with commit 7fd3bb05b73beea1f9840b505aa09beb9c75a8c6
(the first one) applied?

Second with all commits up to 5da11e49df21f21dac25a2491aa788307bdacb6b

And if that still works with commits up to
c1bfcad4b0cf38ce5b00f7ad880d3a13484c123a