r8169: align setting PME with vendor driver

Align setting PME with the vendor driver. PMEnable is writable on
RTL8169 only, on later chip versions it's read-only. PME_SIGNAL is
used on chip versions from RTL8168evl with the exception of the
RTL8168f family.

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