net:phy:dp83640: Move all HW initialization to dp83640_config_init

phy_init_hw not does a full PHY reset after the driver probe has
finished, so any hw initialization done in the probe will be lost.
Part of the timestamping functionality of the dp83640 is set up in the
probe and with that lost, enabling timestamping will cause a PHY
lockup, requiring a hard reset / power cycle to recover.

This patch moves all the HW initialization in dp83640_probe to
dp83640_config_init.

Signed-off-by: Stefan Sørensen <stefan.sorensen@spectralink.com>
Signed-off-by: David S. Miller <davem@davemloft.net>