CONFIG_SOC_LS1021A is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

Freescale LS1021A support

modulename: mach-ls1021a.ko

configname: CONFIG_SOC_LS1021A

Linux Kernel Configuration
└─>Freescale i.MX family
└─>Freescale LS1021A support
In linux kernel since version 3.10 (release Date: 2013-06-30)  
This enables support for Freescale LS1021A processor.

source code: