tsacct: Use ktime_get_ts()

do_posix_clock_monotonic_gettime() is a leftover from the initial
posix timer implementation which maps to ktime_get_ts()

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20140611234606.840900621@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

kernel/tsacct.c

@@ -38,7 +38,7 @@ void bacct_add_tsk(struct user_namespace *user_ns,
 	BUILD_BUG_ON(TS_COMM_LEN < TASK_COMM_LEN);
 
 	/* calculate task elapsed time in timespec */
-	do_posix_clock_monotonic_gettime(&uptime);
+	ktime_get_ts(&uptime);
 	ts = timespec_sub(uptime, tsk->start_time);
 	/* rebase elapsed time to usec (should never be negative) */
 	ac_etime = timespec_to_ns(&ts);