LU-1548 ldiskfs: repostion some items in ldiskfs_inode_info

LU-1548 ldiskfs: repostion some items in ldiskfs_inode_info

Reposition a few items of ldiskfs_inode_info to remove
the alignment hole in the structure, i.e. reduce the size
of this structure, then each slab page can hold more
objects(ldiskfs_inode_info).

Signed-off-by: Wang di <di.wang@whamcloud.com>
Change-Id: I2a4ff44cd98366029dfbee7c4f750e13df8bf7c3
Reviewed-on: http://review.whamcloud.com/3562
Tested-by: Hudson
Reviewed-by: Fan Yong <yong.fan@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>