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

Use Tegra UART for low-level debug

configname: CONFIG_DEBUG_TEGRA_UART

Kernel low-level debugging port
└─>Use Tegra UART for low-level debug
In linux kernel since version 3.1 (release Date: 2011-10-24)  
Say Y here if you want kernel low-level debugging support
on Tegra based platforms.