CONFIG_DEBUG_RCAR_GEN2_SCIF2 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

Kernel low-level debugging messages via SCIF2 on R8A7794

configname: CONFIG_DEBUG_RCAR_GEN2_SCIF2

Kernel low-level debugging port
└─>Kernel low-level debugging messages via SCIF2 on R8A7794
In linux kernel since version 3.19 (release Date: 2015-02-08)  
Say Y here if you want kernel low-level debugging support
via SCIF2 on Renesas R-Car E2 (R8A7794).