arm64: dts: mediatek: mt7986: add support for Wireless Ethernet Dispatch

Introduce wed0 and wed1 nodes in order to enable offloading forwarding
between ethernet and wireless devices on the mt7986 chipset.

Co-developed-by: Bo Jiao <Bo.Jiao@mediatek.com>
Signed-off-by: Bo Jiao <Bo.Jiao@mediatek.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>