drm/nouveau/disp: move outp/conn construction to chipset code

- pre-nv5x doesn't use any of this, has its own version DRM-side
- preparation for GSP-RM

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Acked-by: Danilo Krummrich <me@dakr.org>
Signed-off-by: Lyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230919220442.202488-37-lyude@redhat.com