dt-bindings: serial: Add bindings for nvidia,tegra264-utc

dt-bindings: serial: Add bindings for nvidia,tegra264-utc

The Tegra UTC (UART Trace Controller) allows multiple clients within
the Tegra SoC to share a physical UART interface. It supports up to 16
clients. Each client operates as an independent UART endpoint with a
dedicated interrupt and 128-character TX/RX FIFOs.

Add device tree binding documentation for the Tegra UTC client.

Signed-off-by: Kartik Rajput <kkartik@nvidia.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20250213125612.4705-2-kkartik@nvidia.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>