CONFIG_PPC_PRPMC2800 is not available for thedefaultarchitecture x86.
Result is shown for architecture powerpc

Motorola-PrPMC2800

modulename: prpmc2800.ko

configname: CONFIG_PPC_PRPMC2800

Linux Kernel Configuration
└─>Motorola-PrPMC2800
In linux kernel since version 2.6.22 (release Date: 2007-07-08)  
This option enables support for the Motorola PrPMC2800 board

source code:
arch/powerpc/platforms/embedded6xx/prpmc2800.c