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

Kernel low-level debugging messages via sunXi R_UART

configname: CONFIG_DEBUG_SUNXI_R_UART

Kernel low-level debugging port
└─>Kernel low-level debugging messages via sunXi R_UART
In linux kernel since version 3.17 (release Date: 2014-10-05)  
Say Y here if you want kernel low-level debugging support
on Allwinner A31/A23 based platforms on the R_UART.