If we know what the default value should be then we can test for
that as well as the feature existence.
Signed-off-by: Andrew Jones <drjones@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200120101023.16030-5-drjones@redhat.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>