CONFIG_ARCH_EXYNOS is not available for the selected architecture x86.
Result is shown for architecture arm

Samsung Exynos

modulename: exynos.ko

configname: CONFIG_ARCH_EXYNOS

Linux Kernel Configuration
└─>Samsung Exynos
In linux kernel since version 3.1 (release Date: 2011-10-24)
Support for Samsung Exynos SoCs
source code:
/arch/arm/mach-exynos/