orangefs: simplify orangefs_inode_is_stale

Check whether this is a new inode at location of call.

Raises the question of what to do with an unknown inode type.  Old code
would've marked the inode bad and returned ESTALE.

Signed-off-by: Martin Brandenburg <martin@omnibond.com>
Signed-off-by: Mike Marshall <hubcap@omnibond.com>