uplink-notunnel: two dhcp-requests for a node

[SvenRoederer]

when using the notunnel uplink our node requests 2 ipadresses via dhcp. one for interfave WAN, another for interface ffuplink.
On both requests the same client-id is used (the hostname), which causes error-messages on the uplink-dhcp server.

We can change the default clientid via uci. As the hostname is not known when creating the ffuplink-interface via uci-defaults, I suggest to use a random name, e.g. freifunk-uplink-xxxx

[pmelange]

I think that is a great idea. And once the wizard has been ran, it can be set to ffreifunk-uplink-$HOSTNAME.

I think using a shorter prefix to the hostname (like ffuplink) would be better. Many of the web interfaces from the telecom will cut off the name after X characters.