coccinelle: api: remove kobj_to_dev.cocci script

Using kobj_to_dev() instead of container_of() is not universally
accepted among maintainers as an improvement. The warning leads to
repeated patch submissions that won't be accepted. Remove the script.

Cc: Christoph Hellwig <hch@lst.de>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Denis Efremov <efremov@linux.com>
Cc: Julia Lawall <Julia.Lawall@inria.fr>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>
Acked-by: Jens Axboe <axboe@kernel.dk>
Acked-by: Denis Efremov <efremov@linux.com>