CONFIG_ARCH_EXYNOS5 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

Samsung Exynos5

configname: CONFIG_ARCH_EXYNOS5

Linux Kernel Configuration
└─>Samsung Exynos
└─>Samsung Exynos5
In linux kernel since version 3.1 (release Date: 2011-10-24)  
Samsung Exynos5 (Cortex-A15/A7) SoC based systems


is selected by
CONFIG_SOC_EXYNOS5420