r8169: enable WoL speed down on more chip versions

Call the pll power down function also for chip versions 02..06 and
13..15. The MAC can't be powered down on these chip versions, but at
least they benefit from the speed-down power-saving if WoL is enabled.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>