CONFIG_S5P_DEV_MFC is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

CONFIG_S5P_DEV_MFC (not configurable)

modulename: dev-mfc.ko

and/or

s5p-dev-mfc.ko

configname: CONFIG_S5P_DEV_MFC

Linux Kernel Configuration
└─>S5P_DEV_MFC
In linux kernel since version 3.1 (release Date: 2011-10-24)  
Compile in platform device definitions for MFC

source code:
arch/arm/plat-s5p/dev-mfc.c
depends
 or CONFIG_ARCH_EXYNOS

is depended by
CONFIG_ARCH_EXYNOS