drm/radeon: track memory statistics about VRAM and GTT usage and buffer moves v2

The statistics are:
- VRAM usage in bytes
- GTT usage in bytes
- number of bytes moved by TTM

The last one is actually a counter, so you need to sample it before and after
command submission and take the difference.

This is useful for finding performance bottlenecks. Userspace queries are
also added.

v2: use atomic64_t

Signed-off-by: Marek Olšák <marek.olsak@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>

diff --cc drivers/gpu/drm/radeon/radeon.h
Simple merge

diff --cc drivers/gpu/drm/radeon/radeon_kms.c
Simple merge

diff --cc drivers/gpu/drm/radeon/radeon_object.c
Simple merge

diff --cc drivers/gpu/drm/radeon/radeon_object.h
Simple merge

diff --cc drivers/gpu/drm/radeon/radeon_ttm.c
Simple merge

diff --cc include/uapi/drm/radeon_drm.h
Simple merge