CONFIG_SOC_EXYNOS5420 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

SAMSUNG EXYNOS5420

modulename: clk-exynos5420.ko

and/or

clk-exynos5-subcmu.ko

configname: CONFIG_SOC_EXYNOS5420

Linux Kernel Configuration
└─>SAMSUNG EXYNOS SoCs Support
└─>SAMSUNG EXYNOS5420
In linux kernel since version 3.10 (release Date: 2013-06-30)  
Enable EXYNOS5420 SoC support

source code:
drivers/clk/samsung/clk-exynos5420.c


is selected by
CONFIG_SOC_EXYNOS5800