[XFS] free partially initialized inodes using destroy_inode

To make sure we free the security data inodes need to be freed using the
proper VFS helper (which we also need to export for this). We mark these
inodes bad so we can skip the flush path for them.

SGI-PV: 987246

SGI-Modid: xfs-linux-melb:xfs-kern:32398a

Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
Signed-off-by: David Chinner <david@fromorbit.com>