CONFIG_S5P_DEV_ONENAND is not available for thedefaultarchitecture x86.
Result is shown for architecture arm
default or selected kernelversion does not have config value CONFIG_S5P_DEV_ONENAND.
Result is shown for kernelversion 6.5.1

CONFIG_S5P_DEV_ONENAND (not configurable)

configname: CONFIG_S5P_DEV_ONENAND

Linux Kernel Configuration
└─>S5P_DEV_ONENAND
In linux kernel since version 2.6.37 (release Date: 2011-01-04)  
Compile in platform device definition for OneNAND controller