CONFIG_KERNEL_MODE_NEON is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

Support for NEON in kernel mode

configname: CONFIG_KERNEL_MODE_NEON

Linux Kernel Configuration
└─>Floating point emulation
└─>Support for NEON in kernel mode
In linux kernel since version 3.10 (release Date: 2013-06-30)  
Say Y to include support for NEON in kernel mode.