net: hisilicon: add hix5hd2 mac driver

Add support for the hix5hd2 XGMAC 1Gb ethernet device.
The controller requires two queues for tx and two queues for rx.
Controller fetch buffer from free queue and then push to used queue.
Diver should prepare free queue and free buffer from used queue.

Signed-off-by: Zhangfei Gao <zhangfei.gao@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>