It is never supposed to fail and cannot return an error, so just
have it return the proper type. Have it return 0xff on nothing
available, since that's what would happen on a real bus.
Signed-off-by: Corey Minyard <cminyard@mvista.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>