io_uring/zcrx: fix area release on registration failure

On area registration failure there might be no ifq set and it's not safe
to access area->ifq in the release path without checking it first.

Cc: stable@vger.kernel.org
Fixes: f12ecf5e ("io_uring/zcrx: fix late dma unmap for a dead dev")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/bc02878678a5fec28bc77d33355cdba735418484.1748365640.git.asml.silence@gmail.com


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