time: Complete NTP adjustment threshold judging conditions

The clocksource mult-adjustment threshold is [mult-maxadj, mult+maxadj],
timekeeping_adjust() only deals with the upper threshold, but misses the
lower threshold.

This patch adds the lower threshold judging condition.

Signed-off-by: pang.xunlei <pang.xunlei@linaro.org>
[jstultz: Minor fix for > 80 char line]
Signed-off-by: John Stultz <john.stultz@linaro.org>

kernel/time/timekeeping.c

@@ -1403,7 +1403,8 @@ static void timekeeping_adjust(struct timekeeper *tk, s64 offset)
 	}
 
 	if (unlikely(tk->tkr.clock->maxadj &&
-		(tk->tkr.mult > tk->tkr.clock->mult + tk->tkr.clock->maxadj))) {
+		(abs(tk->tkr.mult - tk->tkr.clock->mult)
+			> tk->tkr.clock->maxadj))) {
 		printk_once(KERN_WARNING
 			"Adjusting %s more than 11%% (%ld vs %ld)\n",
 			tk->tkr.clock->name, (long)tk->tkr.mult,