CONFIG_EXYNOS4_DEV_AHCI is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

CONFIG_EXYNOS4_DEV_AHCI (not configurable)

modulename: dev-ahci.ko

configname: CONFIG_EXYNOS4_DEV_AHCI

Linux Kernel Configuration
└─>EXYNOS4_DEV_AHCI
In linux kernel since version 2.6.39 (release Date: 2011-05-18)  
Compile in platform device definitions for AHCI

source code:
arch/arm/mach-exynos4/dev-ahci.c
depends
CONFIG_ARCH_EXYNOS4 |
| CONFIG_EXYNOS_ATAGS