io_uring: re-assign files with ring fd/file for SQPOLL switch

io_uring: re-assign files with ring fd/file for SQPOLL switch

If we saw a ring flush and noted that we need to reassign the ring fd
and file, then we also need to do the same for the file table.

Fixes: 67b08c1c9ffb ("io_uring: ensure IOSQE_ASYNC file table grabbing works with SQPOLL")
Signed-off-by: Jens Axboe <axboe@kernel.dk>