make sure nd->dir_mode is always initialized after success exit from
link_path_walk(); in case of empty path it did not happen.
Reported-by: NAnant Thazhemadam <anant.thazhemadam@gmail.com>
Tested-by: NAnant Thazhemadam <anant.thazhemadam@gmail.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>