dev: vadc: Add VADC_USR peripheral driver for PMD9650

VADC_USR peripheral driver is used by clients to request
ADC requests on channels such as reading battery voltage,
battery ID, vph_pwr input, coin cell voltage.

The VADC_HC peripheral has updates to configure the channel
properties such as hardware settling delay, setting
absolute or ratiometric calibration type. The driver returns
the raw ADC code and the physical scaled units for the
ADC channel measurement.

Change-Id: Ibde949179fddfb1f72d3b44820a408bf3b1c67c2
4 files changed