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

Toradex Colibri PX27x

modulename: colibri.ko

and/or

pxa2xx_colibri.ko

and/or

colibri-pxa270.ko

configname: CONFIG_MACH_COLIBRI

Linux Kernel Configuration
└─>Intel PXA2xx/PXA3xx Implementations
└─>Toradex Colibri PX27x
In linux kernel since version 2.6.25 (release Date: 2008-04-16)  
source code:
arch/arm/mach-pxa/colibri.c
selects
CONFIG_PXA27x

depends
CONFIG_ARCH_PXA |
NOT | CONFIG_ARCH_PXA_V7