net: socionext: Stop PHY before resetting netsec

In ndo_stop, driver resets the netsec ethernet controller IP.
When the netsec IP is reset, HW running mode turns to NRM mode
and driver has to wait until this mode transition completes.

But mode transition to NRM will not complete if the PHY is
in normal operation state. Netsec IP requires PHY is in
power down state when it is reset.

This modification stops the PHY before resetting netsec.

Together with this modification, phy_addr is stored in netsec_priv
structure because ndev->phydev is not yet ready in ndo_init.

Fixes: 533dd11a ("net: socionext: Add Synquacer NetSec driver")
Signed-off-by: Masahisa Kojima <masahisa.kojima@linaro.org>
Signed-off-by: Yoshitoyo Osaki <osaki.yoshitoyo@socionext.com>
Signed-off-by: David S. Miller <davem@davemloft.net>