io_uring/rsrc: check for nonconsecutive pages

Pages that are from the same folio do not necessarily need to be
consecutive. In that case, we cannot consolidate them into a single bvec
entry. Before applying the huge page optimization from commit 57bebf80
("io_uring/rsrc: optimise registered huge pages"), check that the memory
is actually consecutive.

Cc: stable@vger.kernel.org
Fixes: 57bebf80

 ("io_uring/rsrc: optimise registered huge pages")
Signed-off-by: Tobias Holl <tobias@tholl.xyz>
[axboe: formatting]
Signed-off-by: Jens Axboe <axboe@kernel.dk>