drm/amdgpu: remove static GDS, GWS and OA allocation

As far as we know this was never used by userspace and so should be removed.

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