iio: ak8975: constify ak_def structures

The ak_def structures are never modified, so declare them as const.

Done with the help of Coccinelle.
Signed-off-by: NJulia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: NJonathan Cameron <jic23@kernel.org>

drivers/iio/magnetometer/ak8975.c

@@ -252,7 +252,7 @@ struct ak_def {
 	u8 data_regs[3];
 };
 
-static struct ak_def ak_def_array[AK_MAX_TYPE] = {
+static const struct ak_def ak_def_array[AK_MAX_TYPE] = {
 	{
 		.type = AK8975,
 		.raw_to_gauss = ak8975_raw_to_gauss,
@@ -360,7 +360,7 @@ static struct ak_def ak_def_array[AK_MAX_TYPE] = {
  */
 struct ak8975_data {
 	struct i2c_client	*client;
-	struct ak_def		*def;
+	const struct ak_def	*def;
 	struct attribute_group	attrs;
 	struct mutex		lock;
 	u8			asa[3];