CONFIG_40x is not available for thedefaultarchitecture x86.
Result is shown for architecture powerpc
default or selected kernelversion does not have config value CONFIG_40x.
Result is shown for kernelversion 6.9.9

AMCC 40x

modulename: head_40x.ko

and/or

40x.ko

configname: CONFIG_40x

Processor Type
└─>AMCC 40x
In linux kernel since version 2.6.15 (release Date: 2006-01-02)  
source code:
arch/powerpc/kernel/