default or selected kernelversion does not have config value CONFIG_TEGRA210_EMC.
Result is shown for kernelversion 6.9-rc5

NVIDIA Tegra210 External Memory Controller driver

modulename: tegra210-emc.ko

configname: CONFIG_TEGRA210_EMC

Linux Kernel Configuration
└─>Device Drivers
└─>Memory Controller drivers
└─>NVIDIA Tegra210 External Memory Controller driver
In linux kernel since version 5.1 (release Date: 2019-05-05)  
This driver is for the External Memory Controller (EMC) found on
Tegra210 chips. The EMC controls the external DRAM on the board.
This driver is required to change memory timings / clock rate for
external memory.

source code: