io_uring: add missing REQ_F_COMP_LOCKED for nested requests

commit 9b7adba9 upstream.

When we traverse into failing links or timeouts, we need to ensure we
propagate the REQ_F_COMP_LOCKED flag to ensure that we correctly signal
to the completion side that we already hold the completion lock.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>