rust: drm: gem: clean up GEM state in init failure case

        // SAFETY: `obj.as_raw()` is guaranteed to be valid by the initialization above.

        unsafe { (*obj.as_raw()).funcs = &Self::OBJECT_FUNCS };

        if let Err(err) =

            // SAFETY: The arguments are all valid per the type invariants.

        to_result(unsafe { bindings::drm_gem_object_init(dev.as_raw(), obj.obj.get(), size) })?;

            to_result(unsafe {

                bindings::drm_gem_object_init(dev.as_raw(), obj.obj.get(), size)

            })

        {

            // SAFETY: `drm_gem_object_init()` initializes the private GEM object state before

            // failing, so `drm_gem_private_object_fini()` is the matching cleanup.

            unsafe { bindings::drm_gem_private_object_fini(obj.obj.get()) };

            return Err(err);

        }

        // SAFETY: We will never move out of `Self` as `ARef<Self>` is always treated as pinned.

        let ptr = KBox::into_raw(unsafe { Pin::into_inner_unchecked(obj) });