iio: chemical: sps30: Move symbol exports into IIO_SPS30 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]>
Cc: Tomasz Duszynski <[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/chemical/sps30.c

···
 
 	return devm_iio_device_register(dev, indio_dev);
 }
-EXPORT_SYMBOL_GPL(sps30_probe);
+EXPORT_SYMBOL_NS_GPL(sps30_probe, IIO_SPS30);
 
 MODULE_AUTHOR("Tomasz Duszynski <[e-mail]>");
 MODULE_DESCRIPTION("Sensirion SPS30 particulate matter sensor driver");

drivers/iio/chemical/sps30_i2c.c

···
 MODULE_AUTHOR("Tomasz Duszynski <[e-mail]>");
 MODULE_DESCRIPTION("Sensirion SPS30 particulate matter sensor i2c driver");
 MODULE_LICENSE("GPL v2");
+MODULE_IMPORT_NS(IIO_SPS30);

drivers/iio/chemical/sps30_serial.c

···
 MODULE_AUTHOR("Tomasz Duszynski <[e-mail]>");
 MODULE_DESCRIPTION("Sensirion SPS30 particulate matter sensor serial driver");
 MODULE_LICENSE("GPL v2");
+MODULE_IMPORT_NS(IIO_SPS30);