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

CONFIG_DEBUG_TEGRA_UART (not configurable)

configname: CONFIG_DEBUG_TEGRA_UART

Linux Kernel Configuration
└─>DEBUG_TEGRA_UART
In linux kernel since version 3.1 (release Date: 2011-10-24)