CONFIG_MIPS_FP_SUPPORT is not available for thedefaultarchitecture x86.
Result is shown for architecture mips

Floating Point support

configname: CONFIG_MIPS_FP_SUPPORT

Linux Kernel Configuration
└─>Kernel type
└─>Floating Point support
In linux kernel since version 4.14.326 (release Date: 2023-09-23)  
Select y to include support for floating point in the kernel
including initialization of FPU hardware, FP context save & restore
and emulation of an FPU where necessary. Without this support any
userland program attempting to use floating point instructions will
receive a SIGILL.

If you know that your userland will not attempt to use floating point
instructions then you can say n here to shrink the kernel a little.

If unsure, say y.