tun: add missing rx stats accounting in tun_xdp_act

tun: add missing rx stats accounting in tun_xdp_act

[ Upstream commit f1084c427f55d573fcd5688d9ba7b31b78019716 ]

The TUN can be used as vhost-net backend, and it is necessary to
count the packets transmitted from TUN to vhost-net/virtio-net.
However, there are some places in the receive path that were not
taken into account when using XDP. It would be beneficial to also
include new accounting for successfully received bytes using
dev_sw_netstats_rx_add.

Fixes: 761876c857cb ("tap: XDP support")
Signed-off-by: Yunjian Wang <wangyunjian@huawei.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>