CONFIG_SOC_IMX6SX is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

i.MX6 SoloX support

modulename: cpuidle-imx6sx.ko

and/or

mach-imx6sx.ko

and/or

clk-imx6sx.ko

configname: CONFIG_SOC_IMX6SX

Linux Kernel Configuration
└─>Freescale i.MX family
└─>i.MX6 SoloX support
In linux kernel since version 3.10 (release Date: 2013-06-30)  
This enables support for Freescale i.MX6 SoloX processor.

source code:
arch/arm/mach-imx/cpuidle-imx6sx.c


is selected by
CONFIG_PINCTRL_IMX6SX