arm64: dts: ti: k3-am62a7-sk: Add serial alias

Add alias for mcu_uart0.

Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>
Link: https://lore.kernel.org/r/20250203-topic-am62-serial-aliases-v6-14-v1-2-f26d4124a9f1@baylibre.com


Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>