clocksource/drivers/timer-microchip-pit64b: Add clocksource suspend/resume

Add suspend/resume support for clocksource timer.

Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/1611061165-30180-1-git-send-email-claudiu.beznea@microchip.com