CONFIG_44x is not available for thedefaultarchitecture x86.
Result is shown for architecture powerpc

AMCC 44x, 46x or 47x

modulename: misc_44x.ko

and/or

idle.ko

and/or

44x_mmu.ko

and/or

cpu_setup_44x.ko

configname: CONFIG_44x

Processor Type
└─>AMCC 44x, 46x or 47x
In linux kernel since version 2.6.15 (release Date: 2006-01-02)  
source code:
/arch/powerpc/platforms/44x/

is selected by
CONFIG_DYNAMIC_MEMSTART