CONFIG_S3C_DEV_RTC is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

CONFIG_S3C_DEV_RTC (not configurable)

modulename: dev-rtc.ko

configname: CONFIG_S3C_DEV_RTC

Linux Kernel Configuration
└─>S3C_DEV_RTC
In linux kernel since version 2.6.35 (release Date: 2010-08-01)  
Complie in platform device definition for RTC

source code: