drm/amdgpu: add ELM/BAF DCE11 configs (v2)

Add support for the display configuration on elm/baf.

v2: add missing Stoney case

Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Jammy Zhou <Jammy.Zhou@amd.com>