net: hns: add uniform interface for phy connection

As device_node is only used by DT case, HNS needs to treat the other
cases including ACPI. It needs to use uniform ways to handle both of
DT and ACPI. This patch chooses phy_device, and of_phy_connect and
of_phy_attach are only used by DT case. It needs to use uniform interface
to handle that sequence by both DT and ACPI.

Signed-off-by: Kejian Yan <yankejian@huawei.com>
Signed-off-by: Yisen Zhuang <Yisen.Zhuang@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>