We want to derivate the big AspeedSoCState object in some more
SoC-specific ones. Since the object size will vary, allocate it
dynamically.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Cédric Le Goater <clg@kaod.org>