CONFIG_PPC40x_SIMPLE is not available for thedefaultarchitecture x86.
Result is shown for architecture powerpc

Simple PowerPC 40x board support

modulename: ppc40x_simple.ko

configname: CONFIG_PPC40x_SIMPLE

Linux Kernel Configuration
└─>Simple PowerPC 40x board support
In linux kernel since version 2.6.28 (release Date: 2008-12-24)  
This option enables the simple PowerPC 40x platform support.

source code:
arch/powerpc/platforms/40x/ppc40x_simple.c
depends
CONFIG_40x

is depended by
CONFIG_ACADIA