iio: imu: bno055: Constify struct regmap_bus

`bno055_ser_regmap_bus` is not modified and can be declared as const to
move its data to a read-only section.
Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
Link: https://patch.msgid.link/20240703-iio-cont-regmap_bus-v1-8-34754f355b65@gmail.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/imu/bno055/bno055_ser_core.c

@@ -492,7 +492,7 @@ static const struct serdev_device_ops bno055_ser_serdev_ops = {
 	.write_wakeup = serdev_device_write_wakeup,
 };
 
-static struct regmap_bus bno055_ser_regmap_bus = {
+static const struct regmap_bus bno055_ser_regmap_bus = {
 	.write = bno055_ser_write_reg,
 	.read = bno055_ser_read_reg,
 };