scripts/git.orderfile: Display MAINTAINERS changes first

If we get custom to see MAINTAINERS changes first,
we might catch missing MAINTAINERS updates easier.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20221216225505.26052-1-philmd@linaro.org>