include/linux/mmzone.h: remove unused is_unevictable_lru()

Since commit a0b8cab ("mm: remove lru parameter from __pagevec_lru_add
and remove parts of pagevec API") there's no user of this function anymore,
so remove it.

Signed-off-by: Yaowei Bai <baiyaowei@cmss.chinamobile.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: Yaowei Bai

include/linux/mmzone.h

@@ -195,11 +195,6 @@ static inline int is_active_lru(enum lru_list lru)
 	return (lru == LRU_ACTIVE_ANON || lru == LRU_ACTIVE_FILE);
 }
 
-static inline int is_unevictable_lru(enum lru_list lru)
-{
-	return (lru == LRU_UNEVICTABLE);
-}
-
 struct zone_reclaim_stat {
 	/*
 	 * The pageout code in vmscan.c keeps track of how many of the