Adding support of Lighting GBOX as a target (2 Oculink ports) LiteX board

[ohault]

This device comes with two Artix7 FPGAs and two Oculink ports.
One of the two FPGAs would contain proprietary IPs.

https://github.com/ufrisk/pcileech-fpga/tree/master/GBOX

[enjoy-digital]

Thanks @ohault, we don't currently have this hardware but if you manage to get/provide some, we could probably put in place initial LiteX-Boards support.