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

CONFIG_CPU_FREQ_PXA (not configurable)

configname: CONFIG_CPU_FREQ_PXA

Linux Kernel Configuration
└─>CPU Frequency scaling
└─>CPU_FREQ_PXA
In linux kernel since version 2.6.25 (release Date: 2008-04-16)  
selects
CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE