CONFIG_MACH_TEGRA_DT is not available for thedefaultarchitecture x86.
Result is shown for architecture arm
default or selected kernelversion does not have config value CONFIG_MACH_TEGRA_DT.
Result is shown for kernelversion 6.2.5

Generic Tegra board (FDT support)

modulename: board-dt.ko

and/or

board-harmony-pinmux.ko

configname: CONFIG_MACH_TEGRA_DT

Linux Kernel Configuration
└─>Generic Tegra board (FDT support)
In linux kernel since version 3.1 (release Date: 2011-10-24)  
Support for generic nVidia Tegra boards using Flattened Device Tree

source code:
arch/arm/mach-tegra/board-dt.c
selects
CONFIG_USE_OF