drm/amd/display: Drop unused field from dc_panel_patch

In the struct dc_panel_patch, we have a field named
manage_secondary_link which is not used by any part of the code. This
commit drops the unused field.

Signed-off-by: Nikola Cornij <nikola.cornij@amd.com>
Reviewed-by: Joshua Aberback <Joshua.Aberback@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>