The v variable goes negative for reg < 0x20. Reorder the code
to first sanity check then calculate v and assign intr to make
sanity checkers happy.
Buglink: https://bugs.launchpad.net/qemu/+bug/1902112
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-id: 20201105134112.25119-7-kraxel@redhat.com