Add documentation for LiteX SoC Controller bindings.
Signed-off-by: NPawel Czarnecki <pczarnecki@internships.antmicro.com>
Signed-off-by: NMateusz Holenko <mholenko@antmicro.com>
Reviewed-by: NRob Herring <robh@kernel.org>
Signed-off-by: NStafford Horne <shorne@gmail.com>