fs/proc/uptime.c:uptime_proc_show(): use get_monotonic_boottime()

Change uptime_proc_show() to use get_monotonic_boottime() instead of
do_posix_clock_monotonic_gettime() + monotonic_to_bootbased().
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: John Stultz <johnstul@us.ibm.com>
Cc: Tomas Janousek <tjanouse@redhat.com>
Cc: Tomas Smetana <tsmetana@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/proc/uptime.c

@@ -20,8 +20,7 @@ static int uptime_proc_show(struct seq_file *m, void *v)
 	for_each_possible_cpu(i)
 		idletime += (__force u64) kcpustat_cpu(i).cpustat[CPUTIME_IDLE];
 
-	do_posix_clock_monotonic_gettime(&uptime);
-	monotonic_to_bootbased(&uptime);
+	get_monotonic_boottime(&uptime);
 	nsec = cputime64_to_jiffies64(idletime) * TICK_NSEC;
 	idle.tv_sec = div_u64_rem(nsec, NSEC_PER_SEC, &rem);
 	idle.tv_nsec = rem;