CONFIG_S3C_DEV_I2C6 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

CONFIG_S3C_DEV_I2C6 (not configurable)

modulename: dev-i2c6.ko

configname: CONFIG_S3C_DEV_I2C6

Linux Kernel Configuration
└─>S3C_DEV_I2C6
In linux kernel since version 2.6.37 (release Date: 2011-01-04)  
Compile in platform device definition for I2C controller 6

source code:
depends
CONFIG_PLAT_SAMSUNG |
| CONFIG_SAMSUNG_ATAGS

is depended by
CONFIG_MACH_NURI