CONFIG_ARCH_PXA is not available for the selected architecture x86.
Result is shown for architecture arm

PXA2xx/PXA3xx-based

configname: CONFIG_ARCH_PXA

Linux Kernel Configuration
└─>PXA2xx/PXA3xx-based
In linux kernel since version 2.6.12 )
Support for Intel/Marvell's PXA2xx/PXA3xx processor line.