f2fs: export dir operations for inline dir

This patch exports some dir operations for inline dir, additionally introduces
f2fs_drop_nlink from f2fs_delete_entry for reusing by inline dir function.

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/recovery.c b/fs/f2fs/recovery.c
index ebd0132..843da53 100644
--- a/fs/f2fs/recovery.c
+++ b/fs/f2fs/recovery.c
@@ -111,7 +111,7 @@
 			iput(einode);
 			goto out_unmap_put;
 		}
-		f2fs_delete_entry(de, page, einode);
+		f2fs_delete_entry(de, page, dir, einode);
 		iput(einode);
 		goto retry;
 	}