mt76: connac: move tx initialization/cleanup in mt76_connac module

Move mt76_connac_init_tx_queues and mt76_connac_tx_cleanup routines
in mt76_connac module. This is a preliminary patch to add mt7990
chipset support.

Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Felix Fietkau <nbd@nbd.name>