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

CONFIG_PPC_FPU (not configurable)

modulename: ldstfp.ko

configname: CONFIG_PPC_FPU

Linux Kernel Configuration
└─>Processor support
└─>PPC_FPU
In linux kernel since version 2.6.15 (release Date: 2006-01-02)  
source code:
arch/powerpc/lib/