hw/arm/xlnx-versal: split the xlnx-versal type

hw/arm/xlnx-versal: split the xlnx-versal type

Split the xlnx-versal device into two classes, a base, abstract class
and the existing concrete one. Introduce a VersalVersion type that will
be used across several device models when versal2 implementation is
added.

This is in preparation for versal2 implementation.

Signed-off-by: Luc Michel <luc.michel@amd.com>
Reviewed-by: Francisco Iglesias <francisco.iglesias@amd.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Edgar E. Iglesias <edgar.iglesias@amd.com>
Tested-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-id: 20250926070806.292065-2-luc.michel@amd.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>