Allow constructing the DCE link encoder without DDC,
which means the AUX registers array will be NULL.
This is necessary to support embedded connectors without DDC.
Fixes: 4562236b3b ("drm/amd/dc: Add dc display driver (v2)")
Link: https://gitlab.freedesktop.org/drm/amd/-/work_items/5192
Signed-off-by: Timur Kristóf <timur.kristof@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 87f30b101af62590faf6020d106da07efdda199b)