drm/amdgpu: Add reg headers for DCN314

Register headers for the following IPs:
- DCN 3.1.4
- DPCS 3.1.4

v2:(squash) clean up (Alex)

Signed-off-by: Roman Li <roman.li@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>