this is not something other ISAs do, so clarify it with a comment.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Bastian Koppelmann <kbastian@mail.uni-paderborn.de>
Message-ID: <20230828112651.522058-6-kbastian@mail.uni-paderborn.de>