net: hns: add the support to add/remove the ucast entry to/from table

This patch adds the support to add or remove the unicast entries
to the table and remove from the table.

Reported-by: Daode Huang <huangdaode@hisilicon.com>
Signed-off-by: Kejian Yan <yankejian@huawei.com>
Reviewed-by: Yisen Zhuang <yisen.zhuang@huawei.com>
Signed-off-by: Salil Mehta <salil.mehta@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>