CONFIG_FSL_SOC is not available for thedefaultarchitecture x86.
Result is shown for architecture powerpc

CONFIG_FSL_SOC (not configurable)

modulename: fsl_soc.ko

configname: CONFIG_FSL_SOC

Linux/PowerPC Kernel Configuration
└─>Bus options
└─>FSL_SOC
In linux kernel since version 2.6.16 (release Date: 2006-03-19)  
source code:
arch/powerpc/sysdev/fsl_soc.c