default or selected kernelversion does not have config value CONFIG_MMC_S3C.
Result is shown for kernelversion 6.9.9

Samsung S3C SD/MMC Card Interface support

modulename: s3cmci.ko

configname: CONFIG_MMC_S3C

Linux Kernel Configuration
└─>Device Drivers
└─>MMC/SD/SDIO card support
└─>Samsung S3C SD/MMC Card Interface support
In linux kernel since version 2.6.27 (release Date: 2008-10-09)  
This selects a driver for the MCI interface found in
Samsung's S3C2410, S3C2412, S3C2440, S3C2442 CPUs.
If you have a board based on one of those and a MMC/SD
slot, say Y or M here.

If unsure, say N.

source code:
depends
CONFIG_MMC
CONFIG_ARCH_S3C24XX or CONFIG_COMPILE_TEST
CONFIG_COMPILE_TEST or CONFIG_S3C24XX_DMAC