expanding on ethernet

expanded ethernet mac/phy, more configurability. replaced ethernet.o by the ethernet/ mac/phy files in f1/Makefile.
I'm voting for 
```
eth_mac_set_100Mbits()
eth_mac_set_10Mbits()
```

the name of function should be self descriptive, so it will not need to read entire peripheral documentation what the author of the function really mean.