iio: adc: ad4170-4: Add support for internal temperature sensor

The AD4170-4 has an internal temperature sensor that can be read using the
ADC. Whenever possible, configure an IIO channel to provide the chip's
temperature.

Reviewed-by: Nuno Sá <nuno.sa@analog.com>
Signed-off-by: Marcelo Schmitt <marcelo.schmitt@analog.com>
Link: https://patch.msgid.link/71ac994060cf79a6c49f39b0c7d04c6c9cbbab00.1751895245.git.marcelo.schmitt@analog.com


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