net: ethernet: mtk_wed: introduce wed wo support

Introduce WO chip support to mtk wed driver. MTK WED WO is used to
implement RX Wireless Ethernet Dispatch and offload traffic received by
wlan nic to the wired interface.

Tested-by: Daniel Golle <daniel@makrotopia.org>
Co-developed-by: Sujuan Chen <sujuan.chen@mediatek.com>
Signed-off-by: Sujuan Chen <sujuan.chen@mediatek.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>