hwmon: (i5k_amb) constify pci_device_id

hwmon: (i5k_amb) constify pci_device_id

pci_device_id are not supposed to change at runtime. All functions
working with pci_device_id provided by <linux/pci.h> work with
const pci_device_id. So mark the non-const structs as const.

File size before:
   text	   data	    bss	    dec	    hex	filename
   3562	    320	      8	   3890	    f32	drivers/hwmon/i5k_amb.o

File size After adding 'const':
   text	   data	    bss	    dec	    hex	filename
   3658	    224	      8	   3890	    f32	drivers/hwmon/i5k_amb.o

Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>