Fix leaks on /proc/{*/sched,sched_debug,timer_list,timer_stats}

On every open/close one struct seq_operations leaks.
Kudos to /proc/slab_allocators.

Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>