Introduce a model of the software programming interface (CFU_APB) of
Xilinx Versal's Configuration Frame Unit.

Signed-off-by: Francisco Iglesias <francisco.iglesias@amd.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 20230831165701.2016397-3-francisco.iglesias@amd.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>