net: ethernet: mtk_eth_soc: use napi_consume_skb

Should improve performance, since it can use bulk free

Signed-off-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Ilya Lipnitskiy <ilya.lipnitskiy@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>