CONFIG_ARCH_MX2 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

MX2-based

configname: CONFIG_ARCH_MX2

Freescale CPU family:
└─>MX2-based
In linux kernel since version 2.6.27 (release Date: 2008-10-09)  
This enables support for systems based on the Freescale i.MX2 family

is selected by
CONFIG_FB_IMX