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