arm64: tegra: Add missing alias for NVIDIA IGX Orin

The following error is seen on boot for the NVIDIA IGX Orin platform ...

 serial-tegra 3100000.serial: failed to get alias id, errno -19

Fix this by populating the necessary alias for the serial device.

Fixes: c95711d7 ("arm64: tegra: Add support for IGX Orin")
Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>