drm/amd/display: Add DCN3.1 blocks to the DC Makefile

Preparation for compiling DCN3.1 support.

Acked-by: Huang Rui <ray.huang@amd.com>
Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>