CONFIG_MACH_M28EVK is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

Support DENX M28EVK Platform

modulename: mach-m28evk.ko

configname: CONFIG_MACH_M28EVK

Linux Kernel Configuration
└─>Support DENX M28EVK Platform
In linux kernel since version 3.3 (release Date: 2012-03-18)  
source code:
arch/arm/mach-mxs/mach-m28evk.c

depends
CONFIG_ARCH_MXS