extcon: int3496: Constify acpi_device_id

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

File size before:
   text	   data	    bss	    dec	    hex	filename
   1733	    352	      0	   2085	    825 drivers/extcon/extcon-intel-int3496.o

File size After adding 'const':
   text	   data	    bss	    dec	    hex	filename
   1797	    272	      0	   2069	    815 drivers/extcon/extcon-intel-int3496.o

Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>