[XFS] Fix inode log item use-after-free on forced shutdown

SGI-PV: 959388
SGI-Modid: xfs-linux-melb:xfs-kern:27805a

Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
Signed-off-by: Tim Shimmin <tes@sgi.com>