Some of these date from the very introduction of KMS in 2008 ...
-- drm_display_mode doesn't need to be derived from drm_mode_object. That's
- leftovers from older (never merged into upstream) KMS designs where modes
- where set using their ID, including support to add/remove modes.
-
- Make ->funcs and ->helper_private vtables optional. There's a bunch of empty
function tables in drivers, but before we can remove them we need to make sure
that all the users in helpers and drivers do correctly check for a NULL