CONFIG_ARCH_R8A77990 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm64

Renesas R-Car E3 SoC Platform

configname: CONFIG_ARCH_R8A77990

Linux Kernel Configuration
└─>Platform selection
└─>Renesas R-Car E3 SoC Platform
In linux kernel since version 3.10 (release Date: 2013-06-30)  
This enables support for the Renesas R-Car E3 SoC.