gpu: nvgpu: scheduler management uapi

Add ioctls for creating, removing and querying scheduling domains and
interface with the "nvsched" entity that will be the core scheduler.
Include the scheduler in the Linux build.

The core scheduler code will ultimately hold data on and control what
gets scheduled, but this intermediate layer in nvgpu-rm needs a bit of
bookeeping to manage the userspace interface.

To keep changes isolated, this does not touch the internal runlist
domains yet. The core scheduler logic will eventually control the
runlist domains.

Jira NVGPU-6788

Change-Id: I7b4064edb6205acbac2d8c593dad019d517243ce
Signed-off-by: Alex Waterman <alexw@nvidia.com>
Signed-off-by: Konsta Hölttä <kholtta@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nvgpu/+/2463625
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>

include/uapi/linux/nvgpu.h

@@ -20,6 +20,8 @@
 #include "nvgpu-event.h"
 #include "nvgpu-as.h"
 
+#include "nvgpu-nvs.h"
+
 /*
  * /dev/nvhost-tsg-gpu device
  *