CONFIG_CPU_PXA320 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

PXA320 (codename Monahans-P)

modulename: zylonite_pxa320.ko

and/or

pxa320.ko

configname: CONFIG_CPU_PXA320

Linux Kernel Configuration
└─>Intel PXA2xx/PXA3xx Implementations
└─>Supported PXA3xx Processor Variants
└─>PXA320 (codename Monahans-P)
In linux kernel since version 2.6.24 (release Date: 2008-01-24)  
source code:
arch/arm/mach-pxa/pxa320.c
selects

CONFIG_PXA3xx