VFS/autofs: try_lookup_one_len() does not need any locks

VFS/autofs: try_lookup_one_len() does not need any locks

try_lookup_one_len() is identical to lookup_one_unlocked() except that
it doesn't include the call to lookup_slow().  The latter doesn't need
the inode to be locked, so the former cannot either.

So fix the documentation, remove the WARN_ON and fix the only caller to
not take the lock.

Signed-off-by: NeilBrown <neilb@suse.de>
Link: https://lore.kernel.org/r/174190517441.9342.5956460781380903128@noble.neil.brown.name
Signed-off-by: Christian Brauner <brauner@kernel.org>