CONFIG_CPU_PXA310 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

PXA310 (codename Monahans-LV)

configname: CONFIG_CPU_PXA310

Linux Kernel Configuration
└─>Intel PXA2xx/PXA3xx Implementations
└─>Supported PXA3xx Processor Variants
└─>PXA310 (codename Monahans-LV)
In linux kernel since version 2.6.24 (release Date: 2008-01-24)