drm/amdgpu/display: extend DCN guards

to cover dcn2.x related headers.

Reviewed-by: Zhan Liu <zhan.liu@amd.com>
Tested-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
3 files changed