net: hns: Fix wrong read accesses via Clause 45 MDIO protocol

When reading phy registers via Clause 45 MDIO protocol, after write
address operation, the driver use another write address operation, so
can not read the right value of any phy registers. This patch fixes it.

Signed-off-by: Yonglong Liu <liuyonglong@huawei.com>
Signed-off-by: Peng Li <lipeng321@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>