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

Toradex Colibri PXA270

modulename: colibri-pxa270.ko

and/or

pxa2xx_colibri.ko

configname: CONFIG_MACH_COLIBRI

Linux Kernel Configuration
└─>PXA2xx/PXA3xx-based
└─>Intel PXA2xx/PXA3xx Implementations
└─>Toradex Colibri PXA270
In linux kernel since version 2.6.25 (release Date: 2008-04-16)  
source code:
/arch/arm/mach-pxa/
selects
CONFIG_PXA27x