ice: Fix freeing XDP frames backed by Page Pool

As already mentioned, freeing any &xdp_frame via page_frag_free() is
wrong, as it assumes the frame is backed by either an order-0 page or
a page with no "patrons" behind them, while in fact frames backed by
Page Pool can be redirected to a device, which's driver doesn't use it.
Keep storing a pointer to the raw buffer and then freeing it
unconditionally via page_frag_free() for %XDP_TX frames, but introduce
a separate type in the enum for frames coming through .ndo_xdp_xmit(),
and free them via xdp_return_frame_bulk(). Note that saving xdpf as
xdp_buff->data_hard_start is intentional and is always true when
everything is configured properly.
After this change, %XDP_REDIRECT from a Page Pool based driver to ice
becomes zero-alloc as it should be and horrendous 3.3 Mpps / queue
turn into 6.6, hehe.

Let it go with no "Fixes:" tag as it spans across good 5+ commits and
can't be trivially backported.

Signed-off-by: Alexander Lobakin <[email protected]>
Signed-off-by: Daniel Borkmann <[email protected]>
Acked-by: Maciej Fijalkowski <[email protected]>
Link: https://lore.kernel.org/bpf/[email protected]

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