[XFS] simplify projid check in xfs_rename

Check for the project ID after attaching all inodes to the transaction.
That way the unlock in the error case is done by the transaction subsystem,
which guaratees that is uses the right flags (which was wrong from day one
of this check), and avoids having special code unlocking an array of inodes
with potential duplicates.  Attaching the inode first is the method used
by xfs_rename and the other namespace methods all other error that require
multiple locked inodes.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>