Revert "io_uring: support CQE32 for nop operation"

Revert "io_uring: support CQE32 for nop operation"

This reverts commit 2bb04df7c2af9dad5d28771c723bc39b01cf7df4.

CQE32 nops were used for debugging and benchmarking but it doesn't
target any real use case. Revert it, we can return it back if someone
finds a good way to use it.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/5ff623d84ccb4b3f3b92a3ea41cdcfa612f3d96f.1655224415.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>