timekeeping: Provide internal ktime_t based data

The ktime_t based interfaces are used a lot in performance critical
code pathes. Add ktime_t based data so the interfaces don't have to
convert from the xtime/timespec based data.

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

include/linux/timekeeper_internal.h

@@ -36,6 +36,9 @@ struct timekeeper {
 	/* Clock shifted nano seconds */
 	u64			xtime_nsec;
 
+	/* Monotonic base time */
+	ktime_t			base_mono;
+
 	/* Current CLOCK_REALTIME time in seconds */
 	u64			xtime_sec;
 	/* CLOCK_REALTIME to CLOCK_MONOTONIC offset */