Use of 0x%d - make up our mind as 0x%x

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Acked-by: Eric Auger <eric.auger@redhat.com>
Message-id: 20201014193355.53074-1-dgilbert@redhat.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>