Fixed link mode is returned by hns3_get_link_ksettings. It is
unreasonable.

This patch fixes it by adding some related functions to get link
mode from hardware.
Signed-off-by: NFuyun Liang <liangfuyun1@huawei.com>
Signed-off-by: NPeng Li <lipeng321@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>