selftests/net: temporarily disable io_uring zc test

We're going to change API, to avoid build problems with a couple of
following commits, disable io_uring testing.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/12b7507223df04fbd12aa05fc0cb544b51d7ed79.1662027856.git.asml.silence@gmail.com


Signed-off-by: Jens Axboe <axboe@kernel.dk>