arm64: tegra: Update console for Jetson Xavier and Orin

The Tegra Combined UART (TCU) is the default serial interface for Jetson
Xavier and Orin platforms and so update the bootargs for these platforms
to use the TCU.

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