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

CONFIG_SAMSUNG_DEV_BACKLIGHT (not configurable)

configname: CONFIG_SAMSUNG_DEV_BACKLIGHT

Linux Kernel Configuration
└─>Samsung S3C64XX
└─>SAMSUNG_DEV_BACKLIGHT
In linux kernel since version 3.1 (release Date: 2011-10-24)  
Compile in platform device definition LCD backlight with PWM Timer