net: hns3: add statistics for PFC frames and MAC control frames

In the old firmware version, statistics acquisition of
PFC frames and MAC control frames is not supported.
Add command retrieves statistics for PFC frames and
MAC control frames from the firmware.

Signed-off-by: liuzhongzhu <liuzhongzhu@huawei.com>
Signed-off-by: Peng Li <lipeng321@huawei.com>
Signed-off-by: Huazhong Tan <tanhuazhong@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>