wifi: mt76: mt7915: enable wed for mt7986-wmac chipset

Enable WED tx support for mt7986-wmac chipset available on mt7986 board.

Tested-by: Daniel Golle <daniel@makrotopia.org>
Co-developed-by: Bo Jiao <Bo.Jiao@mediatek.com>
Signed-off-by: Bo Jiao <Bo.Jiao@mediatek.com>
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: Felix Fietkau <nbd@nbd.name>