wifi: mt76: mt7996: add wed rx support

Similar to MT7915, enable Wireless Ethernet Ditpatcher for MT7996
to offload traffic received from the WLAN nic and transmitted on the
LAN one

Co-developed-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Co-developed-by: Sujuan Chen <sujuan.chen@mediatek.com>
Signed-off-by: Sujuan Chen <sujuan.chen@mediatek.com>
Signed-off-by: Bo Jiao <Bo.Jiao@mediatek.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>