network-speed: add lanspeed parameter fg and gf

now /etc/hydraip-devid with parameter lanspeed=fg select
100MBit/s on eth0 and 1000MBit/s on eth1.
/etc/hydraip-devid with parameter lanspeed=gf select
1000MBit/s on eth0 and 100MBit/s on eth1.

Signed-off-by: Eik Binschek <binschek@dresearch-fe.de>