We initially wanted to provide different level of support for the platforms/targets, mainly
to avoid too much maintenance and let each contributor update its contributed platforms and
targets, but it's easier to update all platforms/targets all-together when LiteX evolves or
changes (and that's what has been done on litex-boards since the creation of the repository).
So let just simplify things and avoid this differentiation.
Fomu Hacker supports dual spi, so add a "spiflash4x" definition.
The litex spi_flash module will run this flash in dual mode, because the
`dq` array is only two signals wide.
Signed-off-by: Sean Cross <sean@xobs.io>
