drm/amd/display: Refactor DCCG into component folder

[why]
cleaning up the code refactor requires dccg to be in its own component.

[how]
move all files under newly created dccg folder and fixing the
makefiles.

Reviewed-by: Martin Leung <martin.leung@amd.com>
Acked-by: Tom Chung <chiahsuan.chung@amd.com>
Signed-off-by: Revalla Hari Krishna <harikrishna.revalla@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>