arm64: dts: ti: k3-am642-evm: Describe main_uart1 pins

Describe the main_uart1 pins even though it is a reserved node for
hardware complete description. This is used by other users of device
tree to help configure the SoC per board requirements.

Signed-off-by: Nishanth Menon <nm@ti.com>
Reviewed-by: Roger Quadros <rogerq@kernel.org>
Link: https://lore.kernel.org/r/20230414073328.381336-8-nm@ti.com


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