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 enable support for Freescale LS1021A processor.