iio: imu: bmi160: Move exported symbols to IIO_BMI160 namespace

Avoid unnecessary pollution of the global symbol namespace by
moving library functions in to a specific namespace and import
that into the drivers that make use of the functions.

For more info: https://lwn.net/Articles/760045/

Signed-off-by: Jonathan Cameron <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Reviewed-By: Joe Simmons-Talbott <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jonathan Cameron <[e-mail]>

drivers/iio/imu/bmi160/bmi160_core.c

···
 	.reg_bits = 8,
 	.val_bits = 8,
 };
-EXPORT_SYMBOL(bmi160_regmap_config);
+EXPORT_SYMBOL_NS(bmi160_regmap_config, IIO_BMI160);
 
 struct bmi160_regs {
 	u8 data; /* LSB byte register for X-axis */
···
 				     BMI160_DRDY_INT_EN, enable_bit,
 				     BMI160_NORMAL_WRITE_USLEEP);
 }
-EXPORT_SYMBOL(bmi160_enable_irq);
+EXPORT_SYMBOL_NS(bmi160_enable_irq, IIO_BMI160);
 
 static int bmi160_get_irq(struct fwnode_handle *fwnode, enum bmi160_int_pin *pin)
 {
···
 
 	return devm_iio_device_register(dev, indio_dev);
 }
-EXPORT_SYMBOL_GPL(bmi160_core_probe);
+EXPORT_SYMBOL_NS_GPL(bmi160_core_probe, IIO_BMI160);
 
 MODULE_AUTHOR("Daniel Baluta <[e-mail]>");
 MODULE_DESCRIPTION("Bosch BMI160 driver");

drivers/iio/imu/bmi160/bmi160_i2c.c

···
 MODULE_AUTHOR("Daniel Baluta <[e-mail]>");
 MODULE_DESCRIPTION("BMI160 I2C driver");
 MODULE_LICENSE("GPL v2");
+MODULE_IMPORT_NS(IIO_BMI160);

drivers/iio/imu/bmi160/bmi160_spi.c

···
 MODULE_AUTHOR("Daniel Baluta <[e-mail]");
 MODULE_DESCRIPTION("Bosch BMI160 SPI driver");
 MODULE_LICENSE("GPL v2");
+MODULE_IMPORT_NS(IIO_BMI160);