fvdw firmware on RPi

[fvdw]

@mdi

I have the same opinion on the kernel, I use the arc-arm one and it seems to do ok with the firmware.
We adapted the firmware to allow usb disk to be mounted (automatically, thanks to Jocko, great job) and use as disk for shared folders
The firmware itself runs from the sd card. There is some IO but I think it should be not a problem for the lifetime of the card, we will see. We could let it run fully from usb disk if we want.

I trial image will be release on short notice. We are in the final testing phase