Adding firmware for USB ethernet to RPI install image

[Martin Husemann <martin%duskware.de@localhost>]

Hello,

after some discussion on current-users about the RPI isntall image lacking
support firmware for some usb ethernet devices (and that being the only
way currently to connect the earlier models), I came up with the attached
patch - just copying over all firmware images from /libdata to the image.

Obvious downside: the image grows.

I have no RPI and can not test it, but a release build completes for me.

Another option is to depreciate this image or completely drop it, documenting
use (and resizing) of the pre-installed root image.

Comments?

Martin