Now that all static TypeInfo instances are declared const, prevent that
new non-const instances are created.

Signed-off-by: Bernhard Beschow <shentey@gmail.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20220117145805.173070-3-shentey@gmail.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>