mm: page_isolation: codeclean fix comment and rm unneeded val init

__test_page_isolated_in_pageblock() returns 1 if all pages in the range
are isolated, so fix the comment.  Variable `pfn' will be initialised in
the following loop so remove it.
Signed-off-by: NBob Liu <lliubbo@gmail.com>
Acked-by: NKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

mm/page_isolation.c

@@ -86,7 +86,7 @@ undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn)
  * all pages in [start_pfn...end_pfn) must be in the same zone.
  * zone->lock must be held before call this.
  *
- * Returns 0 if all pages in the range is isolated.
+ * Returns 1 if all pages in the range is isolated.
  */
 static int
 __test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn)
@@ -119,7 +119,6 @@ int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn)
 	struct zone *zone;
 	int ret;
 
-	pfn = start_pfn;
 	/*
 	 * Note: pageblock_nr_page != MAX_ORDER. Then, chunks of free page
 	 * is not aligned to pageblock_nr_pages.