Please share your build steps. What configuration do you use to compile the kernel?
The default PSP configuration for the EVM is am335x_evm_defconfig as shown here: http://processors.wiki.ti.com/index.php/AMSDK_Linux_User%27s_Guide#Using_Default_Configurations
You need to configure the kernel before you compile it and once the kernel is configured a .config file is generated inside the kernel dir. Please note that the file is hidden.
The CONFIG_TI_ADC=y option is enabled by default in this config.
I don't know if your board uses a different configuration or it has on-board EEPROM to simulate the AM335x GP EVM board.
Best regards,
Miroslav