mt76x0: unify tx/rx datapath with mt76x2u driver

Use mt76/mt76-usb shared routine for tx/rx datapath.
Initialize mt76-usb tx/rx queues in mt76x0_init_hardware and
deallocate them in mt76x0_cleanup routine.
Moreover remove data padding in mt76_mac_process_rx routine.
Furthermore remove unused skb2q routine

Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>