hmm_range_fault related fixes and legacy API removal v2

[Jason Gunthorpe]

On Wed, Jul 03, 2019 at 03:02:08PM -0700, Christoph Hellwig wrote:
> Hi Jérôme, Ben and Jason,
> 
> below is a series against the hmm tree which fixes up the mmap_sem
> locking in nouveau and while at it also removes leftover legacy HMM APIs
> only used by nouveau.
> 
> Changes since v1:
>  - don't return the valid state from hmm_range_unregister
>  - additional nouveau cleanups

Ralph, since most of this is nouveau could you contribute a
Tested-by? Thanks

Jason