io_uring/zcrx: netmem array as refiling format

io_uring/zcrx: netmem array as refiling format

Instead of peeking into page pool allocation cache directly or via
net_mp_netmem_place_in_cache(), pass a netmem array around. It's a
better intermediate format, e.g. you can have it on stack and reuse the
refilling code and decouples it from page pools a bit more.

It still points into the page pool directly, there will be no additional
copies. As the next step, we can change the callback prototype to take
the netmem array from page pool.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://patch.msgid.link/9d8549adb7ef6672daf2d8a52858ce5926279a82.1774261953.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>