CONFIG_SOC_IMX31 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm
i.MX31 support
modulename: mm-imx3.ko
configname: CONFIG_SOC_IMX31
Linux Kernel Configuration
└─>Freescale i.MX family
└─>i.MX31 support
In linux kernel since version 2.6.38 (release Date: 2011-03-14)
This enables support for Freescale i.MX31 processor