dt-bindings: iio: adc: mt6359: Add MT6373 PMIC AuxADC

dt-bindings: iio: adc: mt6359: Add MT6373 PMIC AuxADC

Add a compatible and channel bindings for MediaTek's MT6373 PMIC,
featuring an Auxiliary ADC IP with 15 ADC channels for external
(SoC) temperatures and external voltage inputs.

Acked-by: Rob Herring (Arm) <robh@kernel.org>
Reviewed-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Nuno Sá <nuno.sa@analog.com>
Link: https://patch.msgid.link/20250703141146.171431-3-angelogioacchino.delregno@collabora.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>