drm/radeon: remove resource accounting v2

Use the one provided by TTM instead.

v2: drop new_mem parameter as well

Signed-off-by: Christian König <christian.koenig@amd.com>
Tested-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220214093439.2989-5-christian.koenig@amd.com