CONFIG_SOC_KENDRYTE is not available for thedefaultarchitecture x86.
Result is shown for architecture riscv

Kendryte K210 SoC

configname: CONFIG_SOC_KENDRYTE

Linux Kernel Configuration
└─>SoC selection
└─>Kendryte K210 SoC
In linux kernel since version 5.1 (release Date: 2019-05-05)  
This enables support for Kendryte K210 SoC platform hardware.