drm/amd/display: expose DCN401 HUBP functions

[Why]
Expose DCN401 HUBP functions for use across other platforms.

[Description]
This change aims to make the DCN401 HUBP functions accessible for
enabling their use in future platform developments.

Reviewed-by: Alvin Lee <alvin.lee2@amd.com>
Signed-off-by: Karthi Kandasamy <karthi.kandasamy@amd.com>
Signed-off-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>