libxfs: fix argument to xfs_trans_add_item

libxfs: fix argument to xfs_trans_add_item

The hack of casting an inode_log_item or buf_log_item to a
xfs_log_item_t is pretty gross; yes it's the first member in the
structure, but yuk.  Pass in the correct structure member.

This was fixed in the kernel with commit e98c414f9
("xfs: simplify log item descriptor tracking")

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Allison Collins <allison.henderson@oracle.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>