Add a helper to return a machine default CPU type.
If this machine is restricted to a single CPU type,
use it as default, obviously.
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20231116163726.28952-1-philmd@linaro.org>
62b4a227a3