CONFIG_S5P_SLEEP is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

CONFIG_S5P_SLEEP (not configurable)

modulename: s5p-sleep.ko

configname: CONFIG_S5P_SLEEP

Linux Kernel Configuration
└─>S5P_SLEEP
In linux kernel since version 3.1 (release Date: 2011-10-24)  
Internal config node to apply common S5P sleep management code.
Can be selected by S5P and newer SoCs with similar sleep procedure.

source code:
/arch/arm/plat-samsung/