net: ethernet: ave: Increase descriptors to improve performance

To improve performance, this increases Rx descriptor to 256, Tx descriptor
to 64, and adjusts NAPI weight to NAPI_POLL_WEIGHT.

Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
Signed-off-by: David S. Miller <davem@davemloft.net>