Applying the changes to the .cfg file has fixed the problem. The module now boots correctly and reports 4GiB of memory.
For the record, to get our Yocto build, which uses the “meta-tegra” layer to work, I had to apply the patch from the overlay for the file “tegra210-porg-p3448-emc-a00.dtsi” in the “linux-tegra” recipe in “recipes-kernel/linux/linux-tegra”, and also apply a patch generated from “bootloader/t210ref/BCT/P3448_A00_lpddr4_204Mhz_P987.cfg” in the overlay in the recipes “tegra-binaries” and “tegra210-flashtools-native” in “recipies-bsp/tegra-binaries” because both recipes download the file.
Thanks for the help!