net: socionext: netsec: fix xdp stats accounting

Increment netdev rx counters even for XDP_DROP verdict. Report even
tx bytes for xdp buffers (TYPE_NETSEC_XDP_TX or TYPE_NETSEC_XDP_NDO).
Moreover account pending buffer length in netsec_xdp_queue_one as it is
done for skb counterpart

Tested-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>