mt76x2: add napi struct to mt76_rx_poll_complete/mt76_rx_complete signatures

in order to reuse mt76_rx_complete routine supporting mt76x2u based
devices add napi struct to mt76_rx_poll_complete and mt76_rx_complete
routine signatures and do not fetch it according to the rx queue index

Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>