net: hns: bugfix about pfc pause frame statistics

For SoC hip06, PFC pause handled in dsaf, while hip05 in XGMAC,
so change the statistics of pfc pause in dsaf and remove the old
pfc pause frame statistics.

Signed-off-by: Daode Huang <huangdaode@hisilicon.com>
Signed-off-by: Yisen Zhuang <Yisen.Zhuang@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>