CONFIG_S3C_DEV_WDT is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

CONFIG_S3C_DEV_WDT (not configurable)

configname: CONFIG_S3C_DEV_WDT

Linux Kernel Configuration
└─>Samsung Common options
└─>S3C_DEV_WDT
In linux kernel since version 2.6.35 (release Date: 2010-08-01)  
Complie in platform device definition for Watchdog Timer