dt-bindings: iio: magnetometer: Add Voltafield AF8133J

Voltafield AF8133J is a simple magnetometer sensor produced by Voltafield
Technology Corp, with dual power supplies (one for core and one for I/O)
and active-low reset pin.

The sensor has configurable range 1.2 - 2.2 mT and a software controlled
standby mode.

Add a device tree binding for it.

Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
Signed-off-by: Ondřej Jirman <megi@xff.cz>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20240222011341.3232645-3-megi@xff.cz


Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>