io_uring/timeout: fix multishot updates

io_uring/timeout: fix multishot updates

After update only the first shot of a multishot timeout request adheres
to the new timeout value while all subsequent retries continue to use
the old value. Don't forget to update the timeout stored in struct
io_timeout_data.

Cc: stable@vger.kernel.org
Fixes: ea97f6c8558e8 ("io_uring: add support for multishot timeouts")
Reported-by: Christian Mazakas <christian.mazakas@gmail.com>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/e6516c3304eb654ec234cfa65c88a9579861e597.1736015288.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>