CONFIG_SH_ADC is not available for thedefaultarchitecture x86.
Result is shown for architecture sh

ADC support

modulename: adc.ko

configname: CONFIG_SH_ADC

Linux Kernel Configuration
└─>Processor features
└─>ADC support
In linux kernel since version 2.6.12  
Selecting this option will allow the Linux kernel to use SH3 on-chip
ADC module.

If unsure, say N.

source code:
arch/sh/kernel/cpu/adc.c
depends
CONFIG_CPU_SH3