sched/core: Delete PF_EXITING checks from cpu_cgroup_exit() callback

sched/core: Delete PF_EXITING checks from cpu_cgroup_exit() callback

cgroup_exit() is not called from copy_process() after commit:

  e8604cb43690 ("cgroup: fix spurious lockdep warning in cgroup_exit()")

from do_exit(). So this check is useless and the comment is obsolete.

Signed-off-by: Kirill Tkhai <ktkhai@odin.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/55E444C8.3020402@odin.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>