net: hns: Remove the redundant adding and deleting mac function

The functions (hns_dsaf_set_mac_mc_entry() and hns_mac_del_mac()) are
not called by any functions. They are dead code in hns. And the same
features are implemented by the patch (the id is 66355f52).

Reported-by: Weiwei Deng <dengweiwei@huawei.com>
Signed-off-by: Kejian Yan <yankejian@huawei.com>
Reviewed-by: Salil Mehta <salil.mehta@huawei.com>
Signed-off-by: Salil Mehta <salil.mehta@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>