[adc][u-boot] Add support for SARADC access from U-Boot
Enabled command line support in menuconfig for ADC. Enabled SARADC in device-tree. Add code to rockchip_saradc driver to support rk3588 SAR ADC. Fixed that behaviour by adding reset to the driver.
Signed-off-by: Sakhar Andrey andrey.sahar@edws.tech