iio: magnetometer: ak8975: Add AK09118 support

Add additional AK09118 to the magnetometer driver which has the same
register mapping and scaling as the AK09112 device.

Signed-off-by: Danila Tikhonov <danila@jiaxyga.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Barnabás Czémán <barnabas.czeman@mainlining.org>
Link: https://patch.msgid.link/20240819-ak09918-v4-4-f0734d14cfb9@mainlining.org


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