Introduce mt7615_mcu_fill_msg routine to initialize mcu messages.
mt7615_mcu_fill_msg will be reused adding mt7663u support
Co-developed-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Felix Fietkau <nbd@nbd.name>