drm/amdgpu: make sure to reserve tmr region on all asics which support it

This includes older APUs like renoir.

Acked-by: Nirmoy Das <nirmoy.das@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>