drm/amd/display: Introduce New ABC Framework for Brightness Control

Adjust the existing brightness control functions to use the new
ABC Framework and prioritize Aux-based brightness control.

Reviewed-by: Anthony Koo <anthony.koo@amd.com>
Signed-off-by: Muyuan Yang <muyuan.yang@amd.com>
Signed-off-by: Fangzhi Zuo <jerry.zuo@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>