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

Kernel low-level debugging via Meson6 UARTAO

configname: CONFIG_DEBUG_MESON_UARTAO

Kernel low-level debugging port
└─>Kernel low-level debugging via Meson6 UARTAO
In linux kernel since version 3.18 (release Date: 2014-12-07)  
Say Y here if you want kernel low-lever debugging support
on Amlogic Meson6 based platforms on the UARTAO.