io_uring/net: remove extra notif rsrc setup

io_send_zc_prep() sets up notification's rsrc_node when needed, don't
unconditionally install it on notif alloc.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/dbe4875ac33e180b9799d8537a5e27935e82aac4.1667557923.git.asml.silence@gmail.com


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