mm/compaction.c: avoid double mem_cgroup_del_lru()

del_page_from_lru_list() already called mem_cgroup_del_lru().  So we must
not call it again.  It adds unnecessary overhead.

It was not a runtime bug because the TestClearPageCgroupAcctLRU() early in
mem_cgroup_del_lru_list() will prevent any double-deletion, etc.

Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Reviewed-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>