io_uring/zcrx: fix pp destruction warnings

With multiple page pools and in some other cases we can have allocated
niovs on page pool destruction. Remove a misplaced warning checking that
all niovs are returned to zcrx on io_pp_zc_destroy(). It was reported
before but apparently got lost.

Reported-by: Pedro Tammela <pctammela@mojatatu.com>
Fixes: 34a3e60 ("io_uring/zcrx: implement zerocopy receive pp memory provider")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/b9e6d919d2964bc48ddbf8eb52fc9f5d118e9bc1.1751878185.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: isilence

io_uring/zcrx.c

@@ -862,10 +862,7 @@ static int io_pp_zc_init(struct page_pool *pp)
 static void io_pp_zc_destroy(struct page_pool *pp)
 {
 	struct io_zcrx_ifq *ifq = io_pp_to_ifq(pp);
-	struct io_zcrx_area *area = ifq->area;
 
-	if (WARN_ON_ONCE(area->free_count != area->nia.num_niovs))
-		return;
 	percpu_ref_put(&ifq->ctx->refs);
 }