net: ethernet: mediatek: modify to use the PDMA instead of the QDMA for Ethernet RX

Because the PDMA has richer features than the QDMA for Ethernet RX
(such as multiple RX rings, HW LRO, etc.),
the patch modifies to use the PDMA to handle Ethernet RX.

Acked-by: John Crispin <john@phrozen.org>
Signed-off-by: Nelson Chang <nelson.chang@mediatek.com>
Signed-off-by: David S. Miller <davem@davemloft.net>