f2fs: remove redundant judgement condition in available_free_memory

In available_free_memory, there are two same judgement conditions which
is used for checking NAT excess, remove one of them.
Signed-off-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/node.c

@@ -54,8 +54,6 @@ bool available_free_memory(struct f2fs_sb_info *sbi, int type)
 		res = mem_size < ((avail_ram * nm_i->ram_thresh / 100) >> 2);
 		if (excess_cached_nats(sbi))
 			res = false;
-		if (nm_i->nat_cnt > DEF_NAT_CACHE_THRESHOLD)
-			res = false;
 	} else if (type == DIRTY_DENTS) {
 		if (sbi->sb->s_bdi->wb.dirty_exceeded)
 			return false;