hw/clock: Expose 'qtest-clock-period' QOM property for QTests

hw/clock: Expose 'qtest-clock-period' QOM property for QTests

Expose the clock period via the QOM 'qtest-clock-period' property so it
can be used in QTests. This property is only accessible in QTests (not
via HMP).

Signed-off-by: Inès Varhol <ines.varhol@telecom-paris.fr>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Luc Michel <luc@lmichel.fr>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 20241003081105.40836-3-ines.varhol@telecom-paris.fr
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>