delayacct: Make accounting nanosecond based

Kill the timespec juggling and calculate with plain nanoseconds.

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

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

diff --cc kernel/delayacct.c
Simple merge