drm/todo: Improve drm_gem_object funcs todo

We're kinda going in the wrong direction. Spotted while typing better
gem/prime docs.

Cc: Thomas Zimmermann <[e-mail]>
Cc: Gerd Hoffmann <[e-mail]>
Cc: Rob Herring <[e-mail]>
Cc: Noralf Trønnes <[e-mail]>
Reviewed-by: Eric Anholt <[e-mail]>
Acked-by: Gerd Hoffmann <[e-mail]>
Signed-off-by: Daniel Vetter <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

Documentation/gpu/todo.rst

···
 GEM objects can now have a function table instead of having the callbacks on the
 DRM driver struct. This is now the preferred way and drivers can be moved over.
 
+Unfortunately some of the recently added GEM helpers are going in the wrong
+direction by adding OPS macros that use the old, deprecated hooks. See
+DRM_GEM_CMA_VMAP_DRIVER_OPS, DRM_GEM_SHMEM_DRIVER_OPS, and DRM_GEM_VRAM_DRIVER_PRIME.
+
 Use DRM_MODESET_LOCK_ALL_* helpers instead of boilerplate
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