crash_dump: constify struct configfs_item_operations and configfs_group_operations

crash_dump: 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
  16339	  11001	    384	  27724	   6c4c	kernel/crash_dump_dm_crypt.o

After:
=====
   text	   data	    bss	    dec	    hex	filename
  16499	  10841	    384	  27724	   6c4c	kernel/crash_dump_dm_crypt.o

Link: https://lkml.kernel.org/r/d046ee5666d2f6b1a48ca1a222dfbd2f7c44462f.1765735035.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Coiby Xu <coxu@redhat.com>
Tested-by: Coiby Xu <coxu@redhat.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>