net: hns3: fix selftest fail issue for fibre port with autoneg on

When doing selftest for fibre port with autoneg on, the MAC speed
may be incorrect, which may cause the selftest failed. This patch
fixes it by halting autoneg during the selftest.

Fixes: 22f48e24 ("net: hns3: add autoneg and change speed support for fibre port")
Signed-off-by: Jian Shen <shenjian15@huawei.com>
Signed-off-by: Peng Li <lipeng321@huawei.com>
Signed-off-by: Huazhong Tan <tanhuazhong@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>