hugetlb: rename max_hstate to hugetlb_max_hstate

hugetlb: rename max_hstate to hugetlb_max_hstate

This patchset implements a memory controller extension to control HugeTLB
allocations.  The extension allows to limit the HugeTLB usage per control
group and enforces the controller limit during page fault.  Since HugeTLB
doesn't support page reclaim, enforcing the limit at page fault time
implies that, the application will get SIGBUS signal if it tries to access
HugeTLB pages beyond its limit.  This requires the application to know
beforehand how much HugeTLB memory it would require for its use.

The goal is to control how many HugeTLB pages a group of tasks can
allocate.  It can be looked at as an extension of the existing quota
interface which limits the number of HugeTLB pages per hugetlbfs
superblock.  An HPC job scheduler requires jobs to specify their resource
requirements in the job file.  Once their requirements can be met, job
schedulers (such as SLURM) will schedule the job.  We need to make sure
that the jobs won't consume more resources than requested.  If they do we
should either error out or kill the application.

This patch:

Rename max_hstate to hugetlb_max_hstate.  We will be using this from other
subsystems like memcg in later patches.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Hillf Danton <dhillf@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>