dt-bindings: iio: magnetometer: bosch,bmc150_magn: add bmx055 magnetometer binding

dt-bindings: iio: magnetometer: bosch,bmc150_magn: add bmx055 magnetometer binding

Add the device-tree binding for the bosch BMX055 IMU (magnetometer
part), which is compatible with bmc150_magn.

Datasheet: https://cdn.sparkfun.com/assets/b/9/1/f/4/bst-bmx055-ds000_datasheet.pdf
Signed-off-by: Jun Yan <jerrysteve1101@gmail.com>
Reviewed-by: Linus Walleij <linusw@kernel.org>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>