CONFIG_CPU_LLSERIAL_S3C2410 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

CONFIG_CPU_LLSERIAL_S3C2410 (not configurable)

configname: CONFIG_CPU_LLSERIAL_S3C2410

Linux Kernel Configuration
└─>CPU_LLSERIAL_S3C2410
In linux kernel since version 2.6.23 (release Date: 2007-10-09)  
Selected if there is an S3C2410 (or register compatible) serial
low-level implementation needed

depends
CONFIG_PLAT_S3C

is depended by
CONFIG_CPU_S3C2410