mt76: mt76u: stop/free all possible rx queues

Stop/free all configured rx queues (data/mcu) in
mt76u_stop_rx/mt76u_free_rx. This is a preliminary patch to support new
devices (e.g. mt7663u) that rely on a hw queue for mcu messages

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>