hw/misc/debugexit: use runstate API instead of plain exit()

hw/misc/debugexit: use runstate API instead of plain exit()

Directly calling exit() prevents any kind of management or handling.
Instead use the corresponding runstate API.
The default behavior of the runstate API is the same as exit().

Signed-off-by: Thomas Weißschuh <thomas@t-8ch.de>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20240523-debugexit-v1-1-d52fcaf7bf8b@t-8ch.de>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>