net: hns3: fix port capbility updating issue

Currently, the driver queries the media port information, and
updates the port capability periodically. But it sets an error
mac->speed_type value, which stops update port capability.

Fixes: 88d10bd6 ("net: hns3: add support for multiple media type")
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>