mt76x0: remove unused {tx/rx}_queue definitions

Remove unused tx_queue and rx_queue definitions since
now mt76x0 driver uses mt76-usb {tx/rx}_queues

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>