CONFIG_ARCH_RCAR_GEN1 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

CONFIG_ARCH_RCAR_GEN1 (not configurable)

configname: CONFIG_ARCH_RCAR_GEN1

Linux Kernel Configuration
└─>ARCH_RCAR_GEN1
In linux kernel since version 3.10 (release Date: 2013-06-30)