clockevents/drivers/exynos_mct: Implement ->set_state_oneshot_stopped()

set_state_oneshot_stopped() is called by the clkevt core, when the next
event is required at an expiry time of 'KTIME_MAX'. This normally
happens with NO_HZ_{IDLE|FULL} in both LOWRES/HIGHRES modes.

This patch makes the clockevent device to stop on such an event, to
avoid spurious interrupts, as explained by: commit 8fff52fd
("clockevents: Introduce CLOCK_EVT_STATE_ONESHOT_STOPPED state").

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>