On Polarfire SoC, iomux0 is responsible for routing functions to either
Multiprocessor Subsystem (MSS) IOs or to the FPGA fabric, where they
can either interface with custom RTL or be routed to the FPGA fabric's
IOs. Document it.
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>