cobalt/arm: calibrate: prevent excessive delay of next host tick
The calibration procedure overwrites the current value of the timer counter for a pending oneshot tick event, which is admittedly ok in the context of initializing Cobalt. However, the previous implementation maxed the counter value, potentially causing excessive delay to the host waiting for the overwritten timer event. Use a shorter delay value when calibrating so that the next shot does not occur later than one jiffy after we left the calibration routine. One jiffy is also long enough for preventing the timer to ever fire while running the calibration loop.