Reorganize data elements to reduce struct sizes

Thanks for the comments. I have incorportated them all.

CONFIG_OCFS2_FS_STATS is enabled and CONFIG_DEBUG_LOCK_ALLOC is disabled.
Statistics now look like -
ocfs2_write_ctxt: 2144 - 2136 = 8
ocfs2_inode_info: 1960 - 1848 = 112
ocfs2_journal: 168 - 160 = 8
ocfs2_lock_res: 336 - 304 = 32
ocfs2_refcount_tree: 512 - 472 = 40

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.de>
Signed-off-by: Joel Becker <joel.becker@oracle.com>