CONFIG_HEXAGON is not available for thedefaultarchitecture x86.
Result is shown for architecture hexagon

CONFIG_HEXAGON (not configurable)

configname: CONFIG_HEXAGON

Linux Kernel Configuration
└─>HEXAGON
In linux kernel since version 3.1 (release Date: 2011-10-24)  
Qualcomm Hexagon is a processor architecture designed for high
performance and low power across a wide variety of applications.