Add documentation for LiteX SoC Controller bindings.
Signed-off-by: Pawel Czarnecki <pczarnecki@internships.antmicro.com>
Signed-off-by: Mateusz Holenko <mholenko@antmicro.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Stafford Horne <shorne@gmail.com>