partner: add fomu target
partner: add fomu target

This adds the Fomu target back in.  The default BaseSoC supports
various USB methods, and will be updated as more become available.

The debug bridge may optionally be added.

Signed-off-by: Sean Cross <d7e19930cc1f42c2d0781f4d9e6f1fe5891bf9cf@xobs.io>

litex-hub/litex-boards