ocfs2: constify struct configfs_item_operations and configfs_group_operations

ocfs2: constify struct configfs_item_operations and configfs_group_operations

'struct configfs_item_operations' and 'configfs_group_operations' are not
modified in this driver.

Constifying these structures moves some data to a read-only section, so
increases overall security, especially when the structure holds some
function pointers.

On a x86_64, with allmodconfig, as an example:
Before:
======
   text	   data	    bss	    dec	    hex	filename
  74011	  19312	   5280	  98603	  1812b	fs/ocfs2/cluster/heartbeat.o

After:
=====
   text	   data	    bss	    dec	    hex	filename
  74171	  19152	   5280	  98603	  1812b	fs/ocfs2/cluster/heartbeat.o

Link: https://lkml.kernel.org/r/7c7c00ba328e5e514d8debee698154039e9640dd.1765708880.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Acked-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Jun Piao <piaojun@huawei.com>
Cc: Heming Zhao <heming.zhao@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>