RDMA/cma: Constify struct configfs_item_operations and configfs_group_operations

RDMA/cma: 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:
Before:
======
   text	   data	    bss	    dec	    hex	filename
   6677	   2776	     64	   9517	   252d	drivers/infiniband/core/cma_configfs.o

After:
=====
   text	   data	    bss	    dec	    hex	filename
   6901	   2552	     64	   9517	   252d	drivers/infiniband/core/cma_configfs.o

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://patch.msgid.link/6acd9c8a79b868b5e541a7e080a6b4b145e4fd4f.1778923041.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Leon Romanovsky <leon@kernel.org>