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

Accelent Xscale IDP

modulename: idp.ko

configname: CONFIG_ARCH_PXA_IDP

Linux Kernel Configuration
└─>Intel PXA2xx/PXA3xx Implementations
└─>Accelent Xscale IDP
In linux kernel since version 2.6.20 (release Date: 2007-02-04)  
source code:
arch/arm/mach-pxa/idp.c
selects
CONFIG_PXA25x

depends
CONFIG_ARCH_PXA |
| CONFIG_ATAGS or CONFIG_UNUSED_BOARD_FILES