NFSv4: Always do open_to_lock_owner if the lock stateid is uninitialised

The original text in RFC3530 was terribly confusing since it conflated
lockowners and lock stateids. RFC3530bis clarifies that you must use
open_to_lock_owner when there is no lock state for that file+lockowner
combination.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>