f2fs: retain inconsistency information to initiate fsck.f2fs

This patch adds sbi->need_fsck to conduct fsck.f2fs later.
This flag can only be removed by fsck.f2fs.

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 41bdf51..a692304 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -849,6 +849,7 @@
 		atomic_set(&sbi->nr_pages[i], 0);
 
 	sbi->dir_level = DEF_DIR_LEVEL;
+	sbi->need_fsck = false;
 }
 
 /*