CONFIG_CPU_EXYNOS4210 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

Samsung Exynos4210

configname: CONFIG_CPU_EXYNOS4210

Linux Kernel Configuration
└─>Samsung Exynos
└─>Samsung Exynos4210
In linux kernel since version 2.6.39 (release Date: 2011-05-18)  

is depended by
CONFIG_ARCH_EXYNOS4