AMDKFD (AMD GPU compute) support for device cgroup.

[Kasiviswanathan, Harish]

Hi Tejun,

Sorry. Resending these patches as I got distracted with other stuff and
couldn't follow through. As per our previous discussion the plan was to
upstream these changes (mainly patch 3 "Export devcgroup_check_permission")
through Alex Deucher's amd-staging-drm-next and Dave Airlie's drm-next trees. I
am planning to take this route. I have rebased my patches to
amd-staging-drm-next.

You and Roman acked patch 3, it will be great if I can Reviewed-by, so that the
upstream path can be smoother.

Best Regards,
Harish

***** Original note about this patch series for ref. ****

amdkfd (part of amdgpu) driver supports the AMD GPU compute stack. amdkfd
exposes only a single device /dev/kfd even if multiple AMD GPU (compute)
devices exist in a system. However, amdgpu drvier exposes a separate render
device file /dev/dri/renderDN for each device. To participate in device cgroup
amdkfd driver will rely on these rendner device files