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>

diff --cc include/linux/timekeeper_internal.h
Simple merge

diff --cc kernel/time/timekeeping.c
Simple merge