[Buildroot] Add package xf86-driver-displaylink

[Michael Morscher]

Hey crowd,

I'm just working on my pandaboard to get a 7 inch USB monitor to work 
with X-Server... But apparently buildroot misses the driver module for 
that type.
I have another setup with Ubuntu where this driver is provided by a 
package. I can also find the sources but I'm not able to cross compile 
it due to lack of knowledge :(

Any help would be highly appreciated if anyone has got a little spare 
time :) Thank!

Bye
Michael