ovl: fix dentry leak in ovl_indexdir_cleanup()

ovl: fix dentry leak in ovl_indexdir_cleanup()

BugLink: http://bugs.launchpad.net/bugs/1723145
commit dc7ab6773e8171e07f16fd0df0c5eea28c899503 upstream.

index dentry was not released when breaking out of the loop
due to index verification error.

Fixes: 415543d5c64f ("ovl: cleanup bad and stale index entries on mount")
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>