mv643xx_eth with 88E1318S: support Wake on LAN

This has been tested on a qnap TS-119P II. Note that enabling WOL with
"ethtool -s eth0 wol g" is not enough; you also need to tell the PIC
microcontroller inside the qnap that WOL should be enabled by sending
0xF2 with qcontrol(1) and you have to disable EUP ("Energy-using
Products", a European power-saving thing) by sending 0xF4.

Signed-off-by: Michael Stapelberg <michael@stapelberg.de>
Signed-off-by: David S. Miller <davem@davemloft.net>