io_uring: fix reversed nonblock flag for link submission

io_queue_link_head() accepts @force_nonblock flag, but io_ring_submit()
passes something opposite.

Fixes: c576666 ("io_uring: optimize submit_and_wait API")
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

fs/io_uring.c

@@ -2761,7 +2761,7 @@ static int io_ring_submit(struct io_ring_ctx *ctx, unsigned int to_submit,
 
 	if (link)
 		io_queue_link_head(ctx, link, &link->submit, shadow_req,
-					block_for_last);
+					!block_for_last);
 	if (statep)
 		io_submit_state_end(statep);