io_uring/rw: cleanup retry path

io_uring/rw: cleanup retry path

We no longer need to gate a potential retry on whether or not the
context matches our original task, as all read/write operations have
been fully prepared upfront. This means there's never any re-import
needed, and hence we can always retry requests.

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