ktime: Sanitize ktime_to_us/ms conversion

With the plain nanoseconds based ktime_t we can simply use
ktime_divns() instead of going through loops and hoops of
timespec/timeval conversion.

Reported-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>

kernel/time/hrtimer.c

@@ -280,6 +280,7 @@ u64 ktime_divns(const ktime_t kt, s64 div)
 
 	return dclc;
 }
+EXPORT_SYMBOL_GPL(ktime_divns);
 #endif /* BITS_PER_LONG >= 64 */
 
 /*