UBIFS: do not read flash unnecessarily

This fix makes the 'dbg_check_old_index()' function return
immediately if debugging is disabled, instead of executing
incorrect 'goto out' which causes UBIFS to:

1. Allocate memory
2. Read the flash

On every commit. OK, we do not commit that often, but it is
still silly to do unneeded I/O anyway.

Credits to coverity for spotting this silly issue.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>
Cc: stable@kernel.org

fs/ubifs/commit.c

@@ -577,7 +577,7 @@ int dbg_check_old_index(struct ubifs_info *c, struct ubifs_zbranch *zroot)
 	size_t sz;
 
 	if (!(ubifs_chk_flags & UBIFS_CHK_OLD_IDX))
-		goto out;
+		return 0;
 
 	INIT_LIST_HEAD(&list);