net/pch_gpe: Cannot disable ethernet autonegation

When attempting to disable ethernet autonegation via ethtool,
the pch_gpe driver will set software reset bit of PHY chip, But
control register of PHY chip of FRI2 will reenable ethernet autonegation.

Signed-off-by: Wei Yang <w90p710@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>