fscrypt: adjust logging for in-creation inodes

Now that a fscrypt_info may be set up for inodes that are currently
being created and haven't yet had an inode number assigned, avoid
logging confusing messages about "inode 0".

Acked-by: Jeff Layton <jlayton@kernel.org>
Link: https://lore.kernel.org/r/20200917041136.178600-7-ebiggers@kernel.org


Signed-off-by: Eric Biggers <ebiggers@google.com>