Because the PIT is also a proper clocksource, the timekeeping code  is
already able to handle lost ticks.
Reported-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NNicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: NAlexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: NDaniel Lezcano <daniel.lezcano@linaro.org>