CONFIG_MACH_MX31_3DS is not available for thedefaultarchitecture x86.
Result is shown for architecture arm
default or selected kernelversion does not have config value CONFIG_MACH_MX31_3DS.
Result is shown for kernelversion 6.9.9

Support MX31PDK (3DS)

modulename: mach-mx31_3ds.ko

configname: CONFIG_MACH_MX31_3DS

Linux Kernel Configuration
└─>Freescale i.MX family
└─>Support MX31PDK (3DS)
In linux kernel since version 2.6.29 (release Date: 2009-03-23)  
Include support for MX31PDK (3DS) platform. This includes specific
configurations for the board and its peripherals.

source code:
arch/arm/mach-imx/mach-mx31_3ds.c