[PATCH V8 43/43] drm/colorop: Add destroy functions for color pipeline

[Simon Ser]

I would prefer these functions to be introduced together with the
patches adding functions to create objects and adding the new fields.
That way it's easier to check the symmetry and at no point in the
series there are memory leaks.

Additionally, I would avoid using the name "cleanup", which seems to
have different semantics: for instance drm_plane_cleanup() doesn't kfree
the pointer. "destroy" seems more appropriate here.