adc: nordic: move to new DT API and kconfig style

Use the new devicetree API. Remove per-board enabling of ADC_0 by
setting ADC_0 to default y when the 'adc' node label points at an
enabled node of the expected compatible (depending on SoC).

Signed-off-by: Martí Bolívar <marti.bolivar@nordicsemi.no>
26 files changed