sched/cputime: Simplify task_cputime()

sched/cputime: Simplify task_cputime()

Now since fetch_task_cputime() has no other users than task_cputime(),
its code could be used directly in task_cputime().

Moreover since only 2 task_cputime() calls of 17 use a NULL argument,
we can add dummy variables to those calls and remove NULL checks from
task_cputimes().

Also remove NULL checks from task_cputimes_scaled().

Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Michael Neuling <mikey@neuling.org>
Cc: Paul Mackerras <paulus@ozlabs.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1479175612-14718-5-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>