arm64: tegra: Add p3971-0089+p3834-0008 support

The P3971-0089+P3834-0008 is an engineering reference platform for the
Tegra264 SoC.

Link: https://lore.kernel.org/r/20250709231401.3767130-3-thierry.reding@gmail.com


Signed-off-by: Thierry Reding <treding@nvidia.com>