CONFIG_PXA27x is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

CONFIG_PXA27x (not configurable)

modulename: cpufreq-pxa2xx.ko

and/or

mfp-pxa2xx.ko

configname: CONFIG_PXA27x

Linux Kernel Configuration
└─>PXA27x
In linux kernel since version 2.6.20 (release Date: 2007-02-04)  
Select code specific to PXA27x variants

source code:
arch/arm/mach-pxa/cpufreq-pxa2xx.c

depends
CONFIG_ARCH_PXA

is selected by
CONFIG_USB_GADGET_PXA27X