net: hns3: refactor the promisc mode setting

As the HNS3 driver doesn't update the MAC address directly in
function hns3_set_rx_mode() now, it can't know whether the
MAC table is full from __dev_uc_sync() and __dev_mc_sync(),
so it's senseless to handle the overflow promisc here.

This patch removes the handle of overflow promisc from function
hns3_set_rx_mode(), and updates the promisc mode in the service
task.

Signed-off-by: Jian Shen <shenjian15@huawei.com>
Signed-off-by: Huazhong Tan <tanhuazhong@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>