drivers: adc: add ads131m02 adc driver

ADS131M02 is Texas Instruments 2-channel, 24-Bit differential
input ADC which support wide range datarate.
Driver add support for adc read, channel configure, adc sampling
mode configuration and power management.

[1]. https://www.ti.com/lit/ds/symlink/ads131m02.pdf



Signed-off-by: Karthikeyan Krishnasamy <karthikeyan@linumiz.com>