[Nouveau] dev_pagemap related cleanups

[Christoph Hellwig]

On Thu, Jun 13, 2019 at 08:40:46PM +0000, Jason Gunthorpe wrote:
> > Perhaps we should pull those out and resend them through hmm.git?
> 
> It could be done - but how bad is the conflict resolution?

Trivial.  All but one patch just apply using git-am, and the other one
just has a few lines of offsets.

I've also done a preliminary rebase of my series on top of those
patches, and it really nicely helps making the drivers even simpler
and allows using the internal refcount in p2pdma.c as well.