add aca sysfs remove support.

Fixes: 37973b69 ("drm/amdgpu: add aca sysfs support")
Signed-off-by: Yang Wang <kevinyang.wang@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>