net: hns: Fix the process of adding broadcast addresses to tcam

If the multicast mask value in device tree is configured not all
0xff, the broadcast mac will be lost from tcam table after the
execution of command 'ifconfig up'. The address is appended by
hns_ae_start, but will be clear later by hns_nic_set_rx_mode
called in dev_open process.

This patch fixed it by not use the multicast mask when add a
broadcast address.

Fixes: b5996f11 ("net: add Hisilicon Network Subsystem basic ethernet support")
Signed-off-by: Xi Wang <wangxi11@huawei.com>
Signed-off-by: Peng Li <lipeng321@huawei.com>
Signed-off-by: Salil Mehta <salil.mehta@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>