iio: Switch i2c drivers back to use .probe()

After commit b8a1a4cd5a98 ("i2c: Provide a temporary .probe_new()
call-back type"), all drivers being converted to .probe_new() and then
03c835f498b5 ("i2c: Switch .probe() to not take an id parameter") convert
back to (the new) .probe() to be able to eventually drop .probe_new() from
struct i2c_driver.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20230515205048.19561-1-u.kleine-koenig@pengutronix.de
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio:magnetometer:rm3100: Move exports to IIO_RM3100 namespace

In order to avoid unnecessary pollution of the global symbol namespace
move the common/library functions into a specific namespace and import
that into the bus specific device drivers that use them.

For more information see https://lwn.net/Articles/760045/

Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Song Qiang <songqiang1304521@gmail.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20220130205701.334592-13-jic23@kernel.org

iio: magnetometer: Add driver support for PNI RM3100

PNI RM3100 is a high resolution, large signal immunity magnetometer,
composed of 3 single sensors and a processing chip with a MagI2C
interface.

Following functions are available:
- Single-shot measurement from
/sys/bus/iio/devices/iio:deviceX/in_magn_{axis}_raw
- Triggerd buffer measurement.
- DRDY pin for data ready trigger.
- Both i2c and spi interface are supported.
- Both interrupt and polling measurement is supported, depends on if
the 'interrupts' in DT is declared.

Signed-off-by: Song Qiang <songqiang1304521@gmail.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>