Prefer using a well known local first CPU rather than a global one.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20231025065909.57344-1-philmd@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>