media: staging: atomisp: ov2680: 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
  12466	   3120	      8	  15594	   3cea drivers/staging/media/atomisp/i2c/ov2680.o

File size After adding 'const':
   text	   data	    bss	    dec	    hex	filename
  12530	   3056	      8	  15594	   3cea drivers/staging/media/atomisp/i2c/ov2680.o
Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

drivers/staging/media/atomisp/i2c/ov2680.c

@@ -1517,7 +1517,7 @@ static int ov2680_probe(struct i2c_client *client,
 	return ret;
 }
 
-static struct acpi_device_id ov2680_acpi_match[] = {
+static const struct acpi_device_id ov2680_acpi_match[] = {
 	{"XXOV2680"},
 	{"OVTI2680"},
 	{},