drm: Track drm_mm allocators and show leaks on shutdown

drm: Track drm_mm allocators and show leaks on shutdown

We can use the kernel's stack tracer and depot to record the allocation
site of every drm_mm user. Then on shutdown, as well as warning that
allocated nodes still reside with the drm_mm range manager, we can
display who allocated them to aide tracking down the leak.

v2: Move Kconfig around so it lies underneath the DRM options submenu.

Signed-off-by: Chris Wilson <[email protected]>
Reviewed-by: Christian König <[email protected]>
Signed-off-by: Daniel Vetter <[email protected]>
Link: http://patchwork.freedesktop.org/patch/msgid/[email protected]