net: hns3: Refactor mac_init function

It needs initialize mdio in initialization process, but reset process
does not reset mdio, so do not initialize mdio in reset process.
This patch move out the mdio configuration function from the mac_init.
So mac_init can be used both in reset process and initialization process.

Signed-off-by: qumingguang <qumingguang@huawei.com>
Signed-off-by: Lipeng <lipeng321@huawei.com>
Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>