timekeeping: Remove comment that's mostly out of date

Prior to 92bb1fcf (Only
do nanosecond rounding on GENERIC_TIME_VSYSCALL_OLD
systems), the comment here was accuate, but now we can
mostly avoid the extra rounding which causes the unlikey
to be actually likely here.

So remove the out of date comment.
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

kernel/time/timekeeping.c

@@ -1134,16 +1134,6 @@ static void timekeeping_adjust(struct timekeeper *tk, s64 offset)
 		 * we can adjust by 1.
 		 */
 		error >>= 2;
-		/*
-		 * XXX - In update_wall_time, we round up to the next
-		 * nanosecond, and store the amount rounded up into
-		 * the error. This causes the likely below to be unlikely.
-		 *
-		 * The proper fix is to avoid rounding up by using
-		 * the high precision tk->xtime_nsec instead of
-		 * xtime.tv_nsec everywhere. Fixing this will take some
-		 * time.
-		 */
 		if (likely(error <= interval))
 			adj = 1;
 		else