peci: npcm: Constify struct peci_controller_ops​

'struct peci_controller_ops' is not modified in this driver.

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

On a x86_64, with allmodconfig:
Before:
======
   text	   data	    bss	    dec	    hex	filename
   8003	    784	     48	   8835	   2283	drivers/peci/controller/peci-npcm.o

After:
=====
   text	   data	    bss	    dec	    hex	filename
   8003	    776	     48	   8827	   227b	drivers/peci/controller/peci-npcm.o

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Iwona Winiarska <iwona.winiarska@intel.com>
Link: https://lore.kernel.org/r/3c7d455745c2265c19ed02f026dfc9610271d3c2.1725692376.git.christophe.jaillet@wanadoo.fr


Signed-off-by: Iwona Winiarska <iwona.winiarska@intel.com>