Cvitek adc dirver only supports one adc controller now,
but the other adc controller RTCSYS_SARADC is missing.
Signed-off-by: Shicheng Chu <1468559561@qq.com>
Reviewed-by: Chen Wang <unicorn_wang@outlook.com>
The ADC controller needs to be calibrated during the initialization
phase, otherwise the measured voltage value will be inaccurate.
Signed-off-by: Chen Wang <unicorn_wang@outlook.com>