mm: setup_per_zone_inactive_ratio - fix comment and make it __init

The caller of setup_per_zone_inactive_ratio is an __init function.  There
is no need to keep the callee after it completed as well.  Also fix a
comment.
Acked-by: NDavid Rientjes <rientjes@google.com>
Signed-off-by: NCyrill Gorcunov <gorcunov@openvz.org>
Reviewed-by: NMinchan Kim <minchan.kim@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

mm/page_alloc.c

@@ -4440,8 +4440,6 @@ void setup_per_zone_pages_min(void)
 }
 
 /**
- * setup_per_zone_inactive_ratio - called when min_free_kbytes changes.
- *
  * The inactive anon list should be small enough that the VM never has to
  * do too much work, but large enough that each inactive page has a chance
  * to be referenced again before it is swapped out.
@@ -4462,7 +4460,7 @@ void setup_per_zone_pages_min(void)
  *    1TB     101        10GB
  *   10TB     320        32GB
  */
-static void setup_per_zone_inactive_ratio(void)
+static void __init setup_per_zone_inactive_ratio(void)
 {
 	struct zone *zone;